Portal 2 is probably the least impressive game visually on this list, but the added depth offered when played in 3D certainly makes the game world feel more realistic. The lack of all-out action and explosions means this isn't going to wow anyone, but the sense of being in that world is definitely enhanced.
Resident Evil 5
Loved by some, hated by others, Resident Evil 5 is somewhat of a Marmite game. What shouldn't be so divisive is the game's use of 3D. Capcom's action horror title already looked the part on PC, but in 3D the game's hugely diverse locations draw you in. The game's more explosive sequences certainly feel more exciting.