Share your experience!
I had purchased Xperia Arc S on 18 Nov 2011 & upgraded it to ICS on 25 April 2012 through PC companion. Since upgrade the phone is not working smoothly as it used to be with andriod 2.3, undermentioned problems are being faced:
1. Out of 10 incoming calls 2-3 calls cannot be answered as it displays a error message of some file not working. After error message box goes away no call record in there in call log.
2.. During taking snaps / video recording it suddenly says "no camera found"
3.When you write a new message and add recipient and try to send it do not come out from add recipient screen.
4. Games which worked smoothly in Andriod 2.3 have become very slow.
5. Facebook inside Xperia not working even after updating it to latest version.
6. Contacts birthdays from face book not displayed in calendar
7. Screen lock function i.e. pattern or password creates problem and suddenly phone returns to slide lock function without changing the lock option.
8. Screen shot function is now not available.
9. Internal speaker volume seems to have reduced as compared to earlier version.
10. Overall phone smoothness i.e. going from one screen to another ot returning to main screen has become very slow.
Reagrding games... they are not ICS compatible :smileyhappy:, game developers would fix them soon
screenshot ; pwer button + volume down button
Reagrding all other things
format your sd card and reinstall your phone's software using pc companion 
Update/Repair your phone via PCC OR SUS
PCC (PC COMPANION) – Repair your software with this .First do the setup without connecting your mobile to pc.(only connect when you are asked to).
Do it as follow >> PCC > SUPPORT ZONE> SOFTWARE UPDATE> REPAIR SOFTWARE (written with blue)
Thanks for your reply, after reparing the phone software, the present status is as under:
Point 1. Seems solved as no problem till now.
Point 2. Seems solved as no problem till now.
Point 3. Does not seems solved as it was ok till i sent 2-3 messages and from today its the same problem i.e. when u write new message and add recipient and try to send it do not come out from add recipient screen.
Point 4. Games even for ICS are slow
Point 5. Facebook inside xperia working now.
Point 6. Solved.
Point 7. Solved.
Point 8. Unable to get Screen shot function
Point 9. Speaker (internal) volume still less.
Point 10. Overall smoothness is good now.
Great :smileygrin:
3) i will further test it and report it to you
😎 press and hold power button and voulme down button at the same time 