I played through all three of them on the 360, and loved them all. When I compared the PC and Xbox BC the other day, my impression was that the only mentionable downside on the XB version was reduced detail in some med/long distance environment textures, like signs around the Citadel for exampe. But detail and aliasing on characters during conversations and cutscenes was nearly indistinguishable to my eyes, which is either very impressive for the Xbox version, or disappointing for the PC version, depending on how you look at it.
Loading on PC is quicker, though, and excellent
controller support with correct button prompts and mapping has been modded into all three games on the PC for a while