I just played the demo. The game played pretty smooth, and is it me or is the gameplay more snappy? I remember the walking and running to be a bit more slower and methodical on the 360, or maybe it is just the looser sticks playing tricks on me. Also, it appears every character's skin texture dropped a shade lighter. Don't now why they did that.
Anyway, the game's framerate clearly is not locked to 30. You can tell it goes to 60 at times. Tearing is a non issue during gameplay, but I actually saw tearing in the ME1 cinematic FMV. WTF?
The screens clearly show a different lighting system at play in the PS3 port, self shadowing is less harsh than the 360, so you tend to see more of each character's faces during closeups. Shadows are slightly less pixellated than the 360 as well. It is different, clearly, but am not sure this can be considered an 'improvement'. Textures assets appear downright identical, though the 360 has higher contrast, as usual.
All in all, a good port. Other than the slightly faster at times but more variable framerate, it is nigh identical to the 360 version. However, the only way I will double dip is if they remove the goddamn scanning mini game. Goddamn Bioware, what were they smoking when they put it into the game?