IJack Nicholson is apparently Jack Nicholson in every film he's in. I don't care. If I like the actor I like the actor, if I don't, I don't.
Yeah, it's a matter of how good that character is oftentimes. Nicholson in 5 Easy Pieces, Chinatown, Cuckoo's Nest, Shining, Batman, As Good As It Gets, Departed, all pretty much variations on a theme. And he's (rightly) considered one of the greatest actors of all time. Clint Eastwood, Jimmy Stewart, Humphrey Bogart, Max Von Sydow, Paul Newman, George Clooney, etc. etc. etc.
If range equaled critical acclaim, then Boris Karloff would be the undisputed greatest actor in the history of the world (not that he wasn't great at what he did), and guys from Second City Television would be held in way higher regard than your Brad Pitts and Leo Dicaprios.
I've also always been a Tom Cruise fan, by the way. I think his personal life affects way too many folks' opinions about him. But Affleck. . .I was a fan, but after his take on Jack Ryan, Matt Murdock, and then Gigli, I couldn't really support him anymore