I've the Steam version. There are a few gotchas:
- if you have any DLCs, DO NOT install them before running the game at least once and authenticating to your EA account. Else you will get an error message that the CD check failed (funny huh?)
- you should be running the game through the launcher otherwise sound may shut off after the intro movie (bioware logo)
- once the game starts, you may need to alt+tab to its actual window
With the above in mind, performance on my machine is just brilliant. No mouse-look issues. The game only crashed on me once during my many hours of playing. Rated silver on Ubuntu 12.10 64bit.