Share your experience!
I recently upgraded my Arc S to 4.0.3 via the Sony download but since I have experienced constant frustration with Wifi connection and problems loading pages. I find the internet connection drops regularly when either typing the address or waiting for pages to load. This despite sitting 8 feet from the wireless router. Before the upgrade, the connection was a whole lot more stable.
I love many of the changes with ICS but I am disappointed with the faults which appear widespread and even more frustrating is that the problems persist on 4.0.4. COME ON SONY!!! SORT IT OUT!.
Did you try to repair your phone software via PCC?
http://www.sonymobile.com/gb/tools/pc-companion/
Have you tried to update you router firmware?
Have you been able to confirm your Wi-Fi problem with other access points as well?