I'll stick to this generation, but these stick out most to me whether my expectations were inflated or not...

Halo 3 - Worst Halo game I've played in the series and I've played all but ODST.
Fallout 3 - First time I've put hours into something that had zero enjoyment or fun with
Code of Princess - Personal expectations were set too high. Large reason why I wanted a 3DS.
Street Fighter IV - Given hope from friends and I hated it like all of the rest of the series
Borderlands - Was a chore to get through and wouldn't have done had it not been for co-op
Dragon Age - Similar feelings to Fallout 3, but it was just boring and not fun
Star Ocean IV - Worst JRPG I've played possibly ever

That's what I can think of off the top of my head for games that seriously disappointed me.

Uncharted 3 - great, but not as good as the 2nd one
Spyro:Enter the Dragonfly - first Spyro game not made by insomniac and a time constrained development period equals a bad game,
World Cup Soccer 2002 (ps1) - world up soccer 98 was my favorite sports game on the ps1. I thought that 2002 would be so much better. The result was a game that played much worse and looked worse than a game made 4 years earlier. ( I don't know how the ps2 version turned out)

Man, I'm with you there.  But to be fair, it is kind of hard to top SSX3.  So good.


Other disappointing games are:
Megaman X 5,6,7 (haven't played 8). X4 was awesome, introducing the voice acting to the series with anime cutscenes. I wish they had continued with that in X5 and 6 minus the girlie x voice.  X7 was lousy. it did not feel like a megaman x game with the 3d boss battles that weren't done very well...

Zelda Phantom Hourglass and Spirit Tracks... My favourite series ever, but I just hated almost everything about both of these titles.

Tastunoko Vs Capcom... why couldn't they have had english voice overs and kept the cutscenes.

Donkey Kong Barrel Blast... Man I thought it would have been fun but the controls were just terrible.

Mario and Sonic at the 2014 olympics - first game I played in the series... I don't know why I just went into it with great expectations.

Dead Island, I expected a deep survival horror game and... well, you know.

I don't think I'll ever get over how mediocre Perfect Dark Zero was. Both GoldenEye and the first Perfect Dark were masterpieces for their time.

The whole Uncharted series.

GTA 4. Ludicrously overrated game. 98 on meta? Seriously? It was by far the least fun I ever had playing a GTA game. The main character didn't fit into the premise of a GTA game at all, constantly going on about how horrible of a person he was and the terrible things he's done whenever a cutscene came around, but then you hit gameplay and he's proceed to act like total scum (as one tends to do in a GTA game). It was completely out of place and boke the immersion for me. The story was drawn out past it's welcome, and that's probably because there was very little to actually do once you were done with it.

Bioshock. Ya.....I said it. This game bored the crap out of me. I've started it up 3 times. Got an hour in, put it down. Got 3 hours in, put it down. Got 6 hours in, decided never to touch it again. The cool setting everyone raves about doesn't grip me in the least, because guess what.....you only really see or feel you're there when you first go down. After that it's just narrow, dark corridors leading into the occasional lit room. Conflict of harvesting little sisters? What conflict? They're little mutants. The gameplay? At it's best when it goes for the occasional horror themed encounters,but it hardly ever does that, instead opting to just constantly throw screaming crap at your face in the same spots over and over. The story? Nothing interesting happened for at least 6 hours so.....I can't be asked to wait longer than that to get hooked. Fuck it.

MGS4. Snake Eater is one of the greatest games I've ever played. 4 is barely even a game. It's really just one huge fan service series of outrageously long cutscenes. That may be enough for some, but not for me. It brought NOTHING unique or new of it's own to the table. In the end I barely felt like I was involved in what happened. There was probably about 4 hours of actual gameplay. Not good enough Kojima.

There's more, but this is all I have time for right now

Did you play Reach?

100% this

final fantasy 13, yes even after the reviews.

And resident evil 5, yes even after the reviews.