Why this movie doesn't work

Rating: 3/10 (10 February 2013)

Main reason: the (mis)cast
Most critics say Bradley Cooper is good. Well, he may be, but he's just not the role. You don't cast an alpha male to play a frustrated, delusional guy with little emotional experience (ie who giggles when a "bad girl" tells him about her sexual prowess). I know, as an actor he's supposed to be able to play any part, but Bradley Cooper oozes sexuality (and I'm hetero) while he should ooze awkwardness. It's about body language, it's about voice tone. He's just not the guy. Of course it's not like the script actually ask him to play a bi-polar character (only the deceptive pitch does). Where are the lows that he's supposed to endure ? Those depressing moments that mark the face and the body ? Sorry but getting occasionally p.ssed-off is not being bipolar. And yes, they could have made a great comedy with the bi-polar material (and I felt it was there, hidden in some intentions of the script), only not a nice and consensual one like the one I saw.
Same problem with Jennifer Lawrence. She's supposed to be a young promiscuous woman wrecked-down by life, but what we have on screen is more like an aging emo who tries to mimic Dirty Dancing in hot pants. Where are the scenes where she gets drunk and do stupid to things ? And regrets them afterwards ? Yes it could be cliché, but it's the truth of her character. She should have gone from being an manipulative child to a upbeat arrogant b.tch, to catatonic. But like Cooper, J. Lawrence is way too monolithic for the part. Putting an unhappy face 90% of the time and yelling the rest of her scenes is not enough, sorry.
In fact, the only character that doesn't seem out of place is Chris Tucker, because contrary to all other actors, he has a spark of craziness in him (or maybe just a little fantasy).
Anyway, go back in time, book Matthew Broderick in his early thirties and AJ Langer in her late twenties, get rid of all the romcom stuff and shoot this movie right ! Of course, it won't be as glamorous and consensual and probably won't get as many Oscar nominations but at least it will be original.