All depends really on which version you have. There are a couple available (none official) and they are slightly different. Im using Grifs CM7.1 2.3.7 with the update fix flashed. I then installed Google maps 5.8 (as current does not work).
The performance of this is fantastic. No lag in games like angry birds. Quadrant scores (i know its not reliable) between 1700-2000. (instead of stock 550-1100). Flash works (needs to be installed). I have also run the allinone ram script which keeps loads of memory available.
The major downside for me though is the video camera has no light and the battery life is not great. There are a few occasions where it force closes to, but as previously said this is not an official rom. (for that you'll have wait - and it looks like it will be a long wait)
Cant see much difference between this and CM 7.2 (have tried both) but the battery life is much worse on that!
Make sure you flash into recovery and make a Clockworkmod recovery backup before doing anything. You can revert to this if all goes wrong of your not happy with the rom.
Boot into recovery. Perform a factory reset/ Data Wipe. then Wipe Dalvik Cache. Then install update from sd card. (the .zip file with the rom) once complete reboot into recovery again and flash the appropriate update file in the same way. Then boot. (this will take time). If you want to keep your apps install titanium backup and make backups before doing anything. Then when CM7 boots install it again and reinstall apps!
Hope this helps.
Bear in mind that flashing CM changes the file system of your ace to ext4 which if you try to restore to stock rom from CWM it wont work and youll have to flash a rom via odin.
Press thanks if that helped