The basic concept is really good: Make a Smash Bros. clone. Make it with Playstation characters. How can this fail?
Answer: make it so you kill other players by doing instant-kill moves instead of knocking them off the stage. Ironically, the one feature setting it apart from Smash Bros. is also the one that damns it for me. :)
They should have just made a Smash Bros clone.
http://i.imgur.com/mng6Lqf.jpg http://tinyurl.com/mxvh3ut - Taylor Swift: Queen of Pop.
Good concept: Take Minecraft-style building and add competitive class and team-based fps-style combat to it. TF2's popular, how could you go wrong imitating it?
How to screw it up: Reset the map to square zero every time the mission objective is completed to deincentivize building anything. Give one of the classes a jetpack making building fortifications almost entirely pointless.
Brute Force (original Xbox) LA Noire (wasn't that bad, just too repetitive) Fable series Sang-Froid (indie game, I just wish its gameplay was more polished with better graphics/animations. Awesome concept, but they obviously had budget issues)
Dragon Age 2. The premise of its story is quite promising. Focusing on how your character impacted a single city's life, with time skips to show the consequences of your actions, could be quite interesting. The characters are good in theory. The basics of combat are good. However, when it comes to everything else, the game sucks.