Updated: 2012-DEC-03: Include Information about Android 4.0 (ICS) update.

It seems Sharp was the first out of the gate to integrate Japanese phone features with a Smart-Phone OS, with their Galapagos Keitai.  Since then, they have continued with newer models, though they have reverted the brand name back to "Aquos", and other makers such as NEC, Toshiba, Fujitsu, Panasonic, etc., have also come out with more Japanized smart-phone models.  Sony has started catching up, and the Xperia Acro HD now sports some Japanese features, such as:

The storage on this phone is impressive by itself.  After having dealt with Android devices with cramped internal storage, we can testify that it's not fun.  Many manufacturers ignore the issue and include very little internal storage figuring "They can just use an SD card if they need more storage".  Of course certain things have to be installed in the "data folder", so phones that only provide 512MB or so of storage quickly fill up.  With 2GB, there is little worry about.  On the other hand, a phone without an SD card can be useless, as many apps (like the camera, etc.) will only save to an SD card.  By having the "Internal Storage", which is seen by the system and apps as an SD card, the first 10GB of data can be stored without using an SD card at all.  That's plenty of space for music, photos, and video clips.  Still, unlike Apple products, actual SD cards are supported, and can be used to bring the total storage capacity further up.  The only potential downside of this arrangement is that there are three locations where data can be potentially saved, which could be confusing to the user.  Realistically, applications go in the Data Folder, and Photos, Music, etc. can go on the Internal Storage or actual SD card.  For the type of user who is likely to fill up the included space and actually need a larger SD card, they can probably figure out what to store where.

One thing some users might not like about this unit is that (much like the iPhone) the battery is not removable or user replaceable, however this is a trade-off, and the up-side is a larger battery and extended battery life.

The external camera is rated at 12MP, which is decent, but megapixels mean little for such a small sensor size.  The low light sensitivity is also decent, and it suffers less from glare than the iPhone 4, as demonstrated by the comparison below.

The 12MP setting is for a 4:3 ratio, 16:9 ratio requires you to set the quality to 9MP.  The front-facing camera is also a little better than average, at 1.3MP, instead of the typical 640K you frequently see on other phones.  Another special feature is that by holding the camera shutter, the phone will wake up, unlock, and enter camera mode in under a second.  This makes it much better for quick shots than any other phone we have used so far.

The phone ships with headphones of decent quality.  The included headphones have an integrated microphone and button, but no volume control.  They also function as an antenna when using the FM radio feature.  Unfortunately, Sony's own iPhone style headphones do not work, even for listening.  On the Sony Mini and some other Sony phones, there is a place in the settings to change this, but on the Acro HD, there seems to be no such setting.

The performance of this phone is stellar, however the Docomo interface is annoying at best.  Luckily, this can be disabled from one of the utilities, and converted to use the Sony interface instead.  Also, if you are used to phones from Sharp and some of the other makers, you may find yourself needing to load this phone up with many extra applications to make up for the lack of built-in apps that the others have.  For example, the default camera application doesn't even support QR codes.  There doesn't appear to be a built-in dictionary, much less one that can do OCR.  On the up side, there is a relatively decent Sony proprietary Japanese IME bundled, and the built-in English IME also has a "swipe" feature (though you have to enable it).  Another disappointment is that it seems one can't record TV shows from the 1seg tuner.  Most of the features are "No Frills".  On the other hand, this should make for faster software updates, with Android 4.0 around the corner (July 2012, Actually).  This shouldn't be called a "Feature", but Docomo saw fit to leave the Android tethering feature enabled, so it can share its connections with PCs, tablets, etc.

This phone is sold through NTT Docomo.  As is typical, you can buy the phone in one lump sum payment (Currently about 63000 yen), or split it up over 24 or 48 months.  There is no interest charge for splitting the payments over 1 or 2 years, but if you buy it up front, you can get points from the shop you buy it with to spend on something else (a case for your new phone?)  The cheapest phone service is around 900 yen, and the "SP Mode" pack is also required, so in addition to the actual cost of the phone, you are looking at a minimum of around 1500 yen per month without data.  The cheapest data plan is around 600 yen, but includes very little data.  The highest plan is around 5000 yen per month for unlimited use.  Unfortunately, Docomo's ideas of "unlimited" are much more restricted than other carriers, like eMobile.  In fact, if I understood correctly, you have to pay extra to be able to use Skype!  There is a mid-range data plan which starts around 2000 yen per month as well.  The high-end plan and low-end plan both quality for the discount (which is also around 2000 yen), which means you will pay less using the mid-level plan than the low-end data plan, even if you don't use the data at all.

One interesting feature with Docomo is that the "SP Mail" works with WiFi (Though you have to enable this feature via 3G first), meaning you can check your Docomo mail using a WiFi connection without incurring data charges.  This is especially valuable overseas.  If it works with WiFi, it presumably works with other SIM card data connections as well.

Another interesting thing is that this phone among the first that Docomo can unlock which also supports the 1700MHz band that eMobile uses.  In fact, it can use Softbank or eMobile SIM cards in Japan.  More information is available on Docomo's SIM compatibility test page here.

Unlocking Process:

In order to unlock the phone, your contract must be in good standing, and of course the contract must be in your name.  The process can not be done online, so you must go to the shop with both the phone and a valid ID.  After paying the 3150 yen unlocking fee, the staff will power down your handset and insert a special SIM card.  After this, they will look up the unlock code on their computer system and enter it.  Voilla! the phone will be unlocked and ready to use with any SIM card.  You can read their write-up on the conditions (In Japanese, of course) here.

APN Settings:

Some phones can be SIM unlocked, but the APN can't be changed, making effectively useless for data on other networks.  Fortunately, Sony and Docomo have seen fit to leave the APN editing options open.  If you use a non-Docomo SIM (or  Docomo SIM that requires a different APN, such as a computer data card SIM), you must change the APN appropriately in order to use the mobile data connection.  

Data Transfer Testing:

* Note: The LTE SIM worked fine, but the the phone doesn't support LTE, so the data connection was HSPA.

The best way to obtain this phone without a contract from Docomo probably involves various shops in Akihabara or online shops like Rakuten.

Problems:

Update: On Android 2.3, this seems to have been enforced by a separate process.  In Ice Cream Sandwich, the APNs that may be used for tethering are stored in an XML settings file that is only accessible to root.  This means you will have to root your phone if you want to use it for tethering with anything other than the Docomo default settings (and a Docomo SIM).

Operating System:

This model comes with Android 2.3.  While other reviewers can be heard complaining "We are on version 4 now, and this is 2.3?", the reality is that testing new releases against hardware, drivers, etc., takes time.  Sony will want to take time to do it properly, and this phone has additional hardware (like Felica and 1Seg) which will need to be validated.  Docomo will likely take additional time to integrate their included applications with the Android 4.0 (whether want them or not!)  Like it or not, just because Google announces that a new OS is ready doesn't mean that everyone is ready to use it with every app and every phone in each market and carrier.

Also at the time of release, Sony isn't the only one not pushing Android 4.0 - None of the other Japanese makers are on current models.  

That said, Android 2.3 works just fine.  The main things 4.0 seems to add are:

1. NFC support (not relevant for a phone with Felica anyway)

2. More reporting and control over data use. (Nice)

3. Ability to freeze (disable) built-in apps (very nice for carrier apps we don't want!)

4. A new theme and many UI changes - This can be a good thing or a bad thing, depending on how used to Android 2.x you are.  

The update process:

You can update over the air, even by WiFi.  The phone will update to a newer version of Android 2.3.x before rebooting.  Once the reboot is complete, it will find another update, which will be the actual 4.x update.  Assuming you accept the update, it will also download and cause the phone to reboot several times as it undergoes several installation phases.  Please make sure you have a full battery or the phone is plugged into power during this process (hopefully both).  Obviously you can not make calls during this process, so it's best to do when you have free time and don't have to use the phone.

Once the upgrade is complete, the phone will spend quite a while adjusting/converting things in the background, during which time the unit will seem fairly unresponsive.  The temptation to play with it is high, but it is probably a better idea to set it aside for a while.  After a while, it will settle down and performance will be much better.

Notes on Android 4.0:

1. As mentioned above, data reporting and control has been improved.  You can now block certain apps from background mobile data.  This is useful for people on tight data plans who want to stop most data transfer when using mobile, but allow it on WiFi.

2. Also mentioned above, you can now freeze most pre-installed apps you don't want so they won't bother you.  Do do this, go to Settings -> Apps -> All (you may have to slide the menu to see this), and then select the offending app.  In the options, you will see "Uninstall", "Remove Update", or "Freeze", depending on the app type.In order to freeze built-in apps, you have to remove any updates first. Also note that not all apps can be frozen.  Still, this option alone can get rid of the most annoying Docomo apps!  We really didn't need the phone book service using 60% of my battery life, right?

3. The location of "Settings" menu has moved in the Xperia home screen.  It is now accessible via the drop-down status menu by using the small tool icon near the top.

4. Along with the standard OS changes, the Music app has been renamed to "Walkman" by Sony.

5. There are more "Developer Options" exposed now in the settings menu, however some of them can cause problems.  For example, enabling "GPU Rendering" will cause Mobile Suica to stop functioning.

6. You now have a choice between the old Android browser and Chrome.  (Chrome has at least one nice feature over the old browser, when touching the screen in a crowded area, it will explode that part of the screen so that you can accurately select the link you want to follow).

If you want to see what else is new in Android 4.0 in general, please see the link below.