I always thought... Raging Bull was somewhat of an original approach at depicting the boxing genre, although it still remains my favorite Scorsese film, I have recently discovered what an influence Body and Soul must have been on Scorsese's masterpiece. The way both Scorsese and Rossen use blood, sweat, the white lights above, and a shaky camera (very documentary-like) when shooting the fights is very similar. The slow motion is not present in Body and Soul, but other than that the two approaches are quite similar.
The idea of anti-hero is also somewhat present in both: the two characters aren't nearly the greatest guys in the world-- they are greedy, selfish, clueless, and violent . John Garfield's character manages to redeem himself at the end, whereas the Jake LaMotta character never really changes in the end except to bathe in self-pity. There are several buddy squabbles in Body and Soul (both ending in tragic deaths) as well as lusting after more than one girl (much like Raging Bull). John Garfield's Charley you can only pity until he gets wise to his actions after his trainer dies and he ceases to be the dumb fool; however, Jake LaMotta is always the fool: unaware of what the consequences to his actions are. Neither character sees how anything that he does affects those around him--Jake is in it for the glory and the money and Charley is only in it for the money--but we watch, relate to, and root for the protagonists of these films. A huge part of that, I daresay, is how great the acting is in both. DeNiro is incredible and John Garfield is an actor way ahead of his time. Garfield is great in everything he did, although he wasn't given much variety in the roles they let him play. Here he plays the boxer from youth until middle age and the portrayal is believable every step of the way. There is a sweet intensity to Garfield and his acting is much more subtle than many actors of his time. He plays the part beautifully. All in all, what a great film. If you have seen neither Raging Bull nor Body and Soul watch this one first and see how Scorsese is influenced by it, yet then takes the genre to a new artistic level.