I tried a few ICS roms (Deck's and AOKP) and also MIUI v4 on my Evo 4G. None of them are totally stable, there is working camera in some of them.
I don't think things will improve till devices get an ICS kernel which will only happen with an official release.
I am running AOKP on my i777 (at&t GSII), i have also run MIUI v4, Cyanogen and a few others from indp. devs and they are all smooth. With the i777 you can port 99% of i9100 roms over to it and it will work just fine.
A Sammy GSM phone will be your best bet for fully functioning ICS rom. I believe all the GSII variants have ICS, TMO version might be a little behind as well as the skyrocket
Running Task650's AKOP 4-7-12 ROM on my AT&T GS2. No issues except my capacitive buttons are turning on, but I can live with that.
I know with my Vibrant, the capacitive buttons lighting up was because I had gotten notifications... there is a setting, somewhere, where you can disable the light (which is what I did...)
Do you use ICS as your daily driver? Hows the battery life, stability, and GPS?
I am running a Nexus S 4G with AOKP Milestone 4. Everything works great. Just like stock. I havent ran into any problems.
Only issue is I cant get more than 8 or 9 hours of battery life and I been seeing around online people reporting like a full day (24hrs) of use !!! Im pissed about this but I cant seem to find an answer.