So far.. Much smoother than previous. Weather on the lock screen is pretty cool.. No crashes yet multiple apps running and internet still moves well. I am on a non-lte area so I can't speak to that but my data speeds are comparable to 2.3.6. Battery seem much better too.. Tough to say now since I have been playing on it most of the day..
over on xda developers theres a ROM that uses the at&t ICS leak as a base but mostly has aosp features (ie. Stock android) so far example its basically ICS as you would see on a Nexus devices. flashed it friday and there have been daily updates which is nice cause those don't wipe everything. and there is different radios (basically drivers for the wireless radio) that you can install too. that helped a lot! ICS is so beautiful.
by the way. the name of the ROM is Sky ICS 4.2
I don't know if this rom is to blame or not, but my credit card number was stolen within a few hours of typing it in on this phone. I am not running any different apps than I was before. I don't know enough to determine if this leak is really from ATT or if someone modified the original leak with keyloggers.
ive had this rom installed for about 2 weeks and it works great.
I haven’t had any problems with it crashing. Performance seems to be better than stock gingerbread. I also tested the Google GPS app today to see if the voices changed, and they have! Sound a lot better than the crappy turn by turn voice on GB!