Dragon Age: Origins, hands down. I bought it a few days after release for a full price, since it was apparently the second coming of the RPG Jesus Christ, according to the internet and the reviews. What I got, was the worst RPG I played in life (Granted, I'm not even touching bad RPG's like Two Worlds) with lame plot, predictable twists, dull world, unlikeable characters except from Morrigan and Zevran (Wynne is my current holder of 'the worst character-wise NPC companion in RPG's ever' award, beating even Go-To from KotOR II), slow and way too easy combat (cone of cold, kinetic prison, repeat with second mage, Good Fight), with animations that look like ass (seriously, the walking-in-combat animation for female characters is so pathetic, I almost died from laughter the first time I saw it), and the graphic itself that looked like ass.
It's not really that bad game, but my high expectations combined with amount of cash I spent on it ended up with hate-rage that fills me whenever I think about this one. I want my money back.
Incidentally, I bought Dragon Age II few days after the release for a full price, PRECISELY because people were bitching that they changed everything from Origins. They changed everything? Woohoo! Maybe this game will actually be good now! And it was... Until the third act, when the whole story fell apart. Oh well, maybe DA III then, they are on the right track now...