Probably not a classic, but entertaining...

Rating: Null/10 (26 May 2002)

As others have pointed out- the historical inaccuracies are just far too many to count. This is problematic when you're making a movie based on very well known real people, and is incredibly distracting. Be wary of anyone claiming to be a history buff who missed that.
In its favor, it does get across some of the problems with Prohibition, and at least some of its more devastating after-effects. Especially given that this is de Palma, the parallels to our modern drug war are inevitable. And unlike so many Mafia movies, the mobsters are portrayed as villains, not as amusing family men. Thanks to de Niro, you see Capone's charisma, but feel no sympathy.
Unlike quite a few here, I got the fact that many scenes were meant to be HOMAGE, rip-off. I don't love de Palma, but he knows his film, and he knew exactly what he was doing. I enjoyed the nod to the true classic gangster movies.
But even given that, I found the baby carriage scene maddening. The action was great and well-executed, and the unbelievable nature of Garcia's shot didn't bother me. But the thing with the baby was overly heavy-handed and drawn out. Puh-leeze.
I don't think Costner is much of an actor, and his gesture towards a mid-Western accent is about as far as he can go. But his non-acting almost works here, as it does in a few of his other films such as Bull Durham and Field of Dreams. I say almost works because some of his actions seem strangely unmotivated and out of character. I'm referring especially to his throwing Nitti off the building, which is historically completely wrong, and highly questionable from both an ethical and film-making standpoint.

Connery is his usual, but fantastic self. This was definitely one of those "body of work" Oscars, and I'm fine with that.
Overall, this film is over-rated as both a classic and a historical piece. But it is better than most, and is certainly engaging and entertaining.