The cursor is even uglier than in Vista's XP compatibility mode. But this is not a mouse-intensive game, at least not the way I play it. I use the shortcut keys to activate powers and the lefthand diamond keys to move, so clicking is mainly for doors, contacts and dialog boxes. In all other ways it is as good as under Windows, and possbily loads the game and the missions faster. That is the impression I get, though I have not timed it. Load times vary anyway.
In a later play session I got a bug where my character would jump back to the starting point, and synching had no effect. I also could not save changes in screen resolution. At the point, the OS was waiting for reboot after a number of updates, and when I started again after the reboot the error was gone. I do not know yet if that was the reason or if it is a recurring error, or even a result of my messing with the screen modes in-game. It has worked fine since though.
Given that the same game on the same machine in native Vista mode would crash after minutes of play (even after updating the drivers), I think this counts as a win for free software.