To understand the issue with void of warranty:

http://developer.sonymobile.com/services/unlock-bootloader/
http://unlockbootloader.sonymobile.com/

Let's take on following three(3) Sony Mobiles points of view of the void of warranty
1) unlock the boot loader will void the warranty - if you do this, you will void your phone warranty. So, do not do it.
2) unlock the boot loader will remove DRM security keys - unique DRM keys are created for your phone. Unlocking it will permanently remove them. They won't be recovered by firmware update. Without DRM keys, your stock Sony multimedia players like Walkman app and Movies app will no longer play any DRM-locked media content.
3) unlock the boot loader will not give any root access - To gain a root access, you need to have a customized ROM that has been rooted. However, this statement is no longer valid. You can gain root access without even unlocking the bootloader and/or flashing a custom ROM via fastboot commands. This is made possible with a root script via ADB commands, busybox and su (Linux super user mode program). No fastboot commands are used at all. Busybox is need to provide the system tools required to root the phone. A hacker named bin4ry has made this possible. See the link below...

http://www.xperiablog.net/2012/09/14/new-r...ootloaders-too/
http://forum.xda-developers.com/showthread.php?t=1886460
http://www.androidtablets.net/forum/androi...an-devices.html
http://www.pocketdroid.net/universal-root-...peria-included/

http://www.busybox.net/FAQ.html#whatis
http://en.wikipedia.org/wiki/Su_%28Unix%29

To understand what ADB can do:

http://www.hackmyandroid.com/what-is-adb-h...r-computer/1681

Will this new root method void the warranty? Well, no if we rely on Sony Mobiles insistence of unlocking the bootloader to void the warranty since the new method doesn't even unlock the bootloader or even flashing a custom rooted ROM.

If there is a failure in this root method, you can still use SEUS/Sony PC Companion to update to the stock firmware without any trouble which it will unroot your phone. Please, do a backup properly before proceed.

Anyway, I will put a disclaimer on this since Sony Mobile hasn't provide any news regarding this new root method.

Great! No more obvious lags unlike before the new root method.

About the clockspeed issue in ICS, I know it from somewhere but I dont know how to verify it. What I can see that the phone is now clocked at 1000MHz rather than 200MHz based on the AndroSensor app in its device info section.

If you are afraid of the advanced approach via the developer option (root or whatever) when you have a lag issue with your ICS update, try the repair option on SEUS/Sony PC Companion to resolve the lag issue. Possibly, it will work. Always make a backup before any update/repair. Disable any antivirus app before any update/repair.

http://talk.sonymobile.com/thread/41810?start=0&tstart=0

Give and take the new ics is much more stable altgough after a while it lag a little but just reboot your phone will solve the lag so reboot your phone once a day will make your life less lag hahaha

Here is my video

The ICS update doesn't looks good from the video above IMHO.
Let me get this right, without rooting the phone, the phone will be clocked at 200Mhz and there is no way to change it back to 1Ghz?

i just hope Sony will update to latest JB near future.

part of my contribution as well on ICS update performance

sorry i can't give the best quality on the video capture though 

i didn't root anything at all,
It is still on official ICS and official rom

just received my phone from warranty claim... (replace one to one new unit)

OMG.. when i turn on.. it's on ICS.. and it's FUGLY and LAGGY..

it's like the screen not sharp with those icons inside.. the previous OS is much better larh..

How many of you have this issue with ICS on Xperia Go?

The 'Settings' app crashes whenever we select Apps -> Running. It says "Unfortunately, Settings has stopped'

http://www.gsmarena.com/sony_announces_whi...n-news-4970.php

 

Well this is informed before but now it is official
i am happy