And a purchase that didn't dissappoint I am certain. The game is a gem.

I'll just keep it simple... Most of Nintendo's Gamecube lineup, with particular disappointment reserved for Double Dash and Sunshine.

Metroid: Other M. It's amazing how it didn't manage to meet my expectations even after they were lowered to subterranean levels.

Metal Slug 4. It's like a juggling circus monkey. It's king of cute in its own way, but it's performing right after The Beatles.

Hehe, opinions can be a bitch sometimes :P

Bioshock 2 will be for me, not because it was a bad game but because it could not live up to the original.

I remember playing the first hour of the game thinking "this is just a carbon copy, this adds nothing new".

The multiplayer was a fun distraction for a weekend, I am not against games adding multiplayer but again, considering how fresh the first game felt even the multiplayer in number 2 just felt like it borrowed too heavily from Shadowrun and Team Fortress

Thanks for reminding me!!!

Chrono Cross. It was an okay RPG but with many issues, it's not worthy of the Chrono name. When you're expected the follow-up the Chrono Trigger you can't help but feel terribly disappointed.

Crash Bash
Star Wars: KOTOR2 
Heavenly Sword 2.... wait?
Metal Gear Solid 4 (partly)
Halo Reach (only ever played Halo 1 and loved it, then played Reach.. my god)
Roller Coaster Tycoon 3

Uncharted 3
God of War 3
Halo 3
Dragon Age II
Final Fantasy VII, XIII, XIII-2
Call of Duty MW3
Paper Mario TYD
Dance Central 2
Soul Calibur V

You're damn right it is.

OP must be trolling. Prime 3 a disappointing sequel??? HELL NO! Best in the series by far!

Now if you wanna talk about disappointing sequels, Prime 2 says hi. Even more crappy backtracking, but this time you have to do it in both light and dark versions of the same areas... oh, like we haven't done THAT a million times before!

And Zelda II disappointing? Hell naw... I'll take this one over the original LOZ any day. Better music, better graphics, I actually like what Nintendo did trying to mix it up with the 2D sidescrolling and RPG elements with top-down view overworld. The only downside to it was it's insane level of difficulty.

For me, most disappointing sequel has to be SSB Brawl and Banjo Nuts & Bolts. One didn't even come close to living up to the insane hype that built up to its release, the other was just a poorly executed mish-mash of ideas that, if released 10 or maybe even 5 years earlier, would have probably been an AAA masterpiece.