Just a bit of thread necromancy here, but too add a few more to the list. Army of Two 40th day. Dantes Inferno {The only thing that was beautiful, was that they stuck true to the Original books world designs} The Saboteur,

Aliens Vs Predator {Spoiler} All three campaigns are really short, the marine campaign is too freaking easy since nothing can touch you, the alien campaign is only seven missions long and will only take about two or three hours depending on how well you can stealth. And the predator campaigns just. Well. Simple. {Spoiler}

I did like the ending of "Saw" [spoilers] Once more you get a choice, if you take the "let him go free" Option, you go home, see a cut scene, guy blows his own head off for giving up on his capture. If you choose to continue to chase jigsaw, bam, its not really jigsaw and you end up costing the life of another girl, who was trying to redeem herself and forgive you. Shotguns baby![/spoilers]

Bioshock two was also a huge letdown at its end. [spoilers] You die and get your essence pulled out by the "Biggest sister" who turns out to be the little sister you were protecting all along, and trying to find. And you're actions dictate how she will lead the rest of her life [/spoilers] Yeah.

Halo 2 was had the worst ending i've ever seen. I hated after you fight the easiest of easy bosses Master Cheif was all "It's not over yet" leading into halo 3 being the worst story of all the halo games. Just terrible.

goonies 2 had the worst ending you like save anna who turns out to be a mermaid its like ohh man tell me konami how can three bad guys capture a mermaid it like impossible.
worst of all the goonies whom you rescued are waiting by the beach.

P.O.W for the arcade had a bad ending, well actually no ending i think when your helicopter comes it doesn't help you shoot the bad guys I'm like oh my got.