Overrated: Dragon Age (same typical bioware storyline, more on the linear side)
Underrated: AC2 (i didn't play this till last week, guess the horrible memory from AC1 still scares me till then)

as for ppl voting for UC2 as overrated, well to me the story is epic. it pays homage to indiana jones and other great adventure movies.

the multiplayer is awesome. the technical advantage makes me wonder why can't more developers make games that's that good.