Problem i've had is that it brings out the flaws in some games, for example i never realized when i played on a low FPS, but bioshock actually has some pretty awful ragdoll physics, when i saw them originally i just assumed the low frame rate made it look weird, however when i saw it run fluidly it just made it look worse.
Bioshock also has some pretty appalling textures and polycounts. Try shooting a splicer in a well lit area then actually looking at the body. Made out of about 10 badly textured polygons
