That hotel room/furry wall scene was ****ing hilarious, and Diddy really did surprise me with his comedic timing...definitely not just a cheap 'name' to bring in cash.
I think, though, Forgetting Sarah Marshall had a better story arc and character development...for a comedy.
It seemed a bit stop/start, and there wasn't enough of a build up of actually getting him to the Greek...I didn't feel there was a point where Brand's character genuinely might not make it. It was just a song and dance coaxing him along.
Maybe it needed a scene where Brand was in real crisis, like perhaps him OD'ing. Not half-arsedly standing on a roof and breaking his arm.
I dunno, it just needed a bit more of a 'YEAHHH HE MADE IT', however cheesy it sounRAB.