Hmmm, this sounds familiar... a young up and comer in the music biz is charged with getting a famously drunken and drugged up rock star to a comeback concert and comic chaos ensues... Anyone recall Richard Benjamin's "My Favorite Year" (1982)? It starred Peter O'Toole as Alan Swann (a character based on Erol Flynn) a drunken matinee idol who is to appear on a live 1950's U.S. TV show. Young Benjy Stone (a character based on Mel Brooks) is the TV show's junior writer who is charged with getting the drunken movie star to the TV show... Easier said than done!
And just like "My Favorite Year" the idea is fine and delivers a few fun scenes (notably Jonah Hill tripping out and cuddling furry wallpaper...) and some nice back n forth between stars Jonah Hill and Russell Brand, but it's all pretty tired. Hats off to Sean 'P. Diddy' 'Puff Daddy' Combs who does a great turn as a music mogul - simultaneously playing and poking fun at himself. As a stoner farce it works well, but it's no great shakes. For pure rock comedy give me SPINAL TAP every time! Mind you, it's better than FORGETTING SARAH MARSHALL - so 3 stars for being a spin-off that beats its original hands down :)