I'm using GodzillaROM, which is based on BobZHome's. Battery life is at least as good (perhaps a bit better?) than I had with CM7 (which, in turn, was better than stock). Performance is good. I've had a few random reboots, but it's not a major problem.
The biggest problem I've had, which I haven't heard mentioned here, is with Gmail. Frequently, when I open an email, it will display the contents for a split-second, and then they will vanish. The message body will turn completely white. Once this starts, it will happen with every message. Force-quitting gmail doesn't help, clearing data doesn't help. Rebooting helps, and sometimes the problem will correct itself randomly, but it always comes back eventually. I've switched to K-9 Mail for now. I've Googled around and found a number of people with this problem, on various hardware. No solutions known.
Another problem is that 3G occasionally dies when coming out of a no-signal zone (like the subway). Turning Airplane Mode on and off doesn't help, but going into the settings and turning mobile data off and back on DOES fix the problem. This doesn't happen very often, and since there's a quick fix when it does, I don't mind so much.
The lack of USB tethering is a big bummer, since I used that often. I can still do wifi tethering with Barnacle, though.
I tried CM10, but it was very slow and had poor stability. It did work, but the pros were few and the cons were many, so I went back to ICS. Maybe I had bad luck. I'll try again with the next version.
I do occasionally get the "insufficient storage" message when installing/updating apps. I'm not sure why. I used Titanium Backup to batch-move a bunch of apps to the SD card. It seemed to work.