It's pretty obvious why Christopher Knight was cast as the lead in this, his breakout film. Marlon Brando, not yet the flabby caricature he'd become in later years, was A-list box-office gold, and Knight looks, sounds and acts like Brando. Well, he kinda sorta does, in the same way that George Lazenby is near-as-dammit Sean Connery. It's also not hard to guess why Knight's cinematic career ended after only one more movie. He's terrible. He tries so very, very hard to be Brando that I felt a bit sorry for him, but the face-pulling he frequently indulges in is downright comical, especially in scenes where he's trying to appear heartbroken. If he was a comedian doing a Brando parody, he'd be superb. As a substitute for the genuine article, he stinks!
His character isn't very appealing either, and not in a good way. Studs is a borderline moronic man-child who, five minutes before the end of the film, finally figures out that maybe he shouldn't be so selfish all the time, and he probably shouldn't still be living with his parents at the age of 28. For the previous hour and a half, he mostly feels sorry for himself, often at unnecessary length in voiceover, or hangs out with his obnoxiously immature buddies, two of whom are a criminally underused Jack Nicholson, who would have been infinitely better than Knight in the lead rôle, and an equally wasted Frank Gorshin (hey, two future Batman villains in the same movie!). They spend their days and nights playing pool, getting drunk (not many actors can act drunk really well, but Knight is exceptionally bad, and he has to do a great deal of of it), or coming up with ever nastier ways to be appallingly sexist.
Strangely for a supposedly gritty tale of a young man growing up in a tough neighborhood during the roaring twenties, there's absolutely no violence or physical danger (the only death in the film is the result of a random off-screen road accident), and although there is quite a lot of sex, it's portrayed so carefully that sometimes we have to be told what just happened. If the source novel was banned in several countries, I can only assume this version was heavily censored! What we're left with is the story of a dull and unpleasant young man's decade-long journey to the realization that he's not the centre of the Universe, and what's more, he's rather thick. Or, if you want to look at it another way, one actor's epic struggle to be another, far better actor. Studs takes ten whole years to figure out that it's time he grew up. Presumably the actor who played him had five times his IQ, since it only took Christopher Knight two years to accept the bitter truth that he wasn't Brando.