Dhruin
SasqWatch
GameSpy has a comparison of Torchlight II and Diablo III from PAX. It's not a very deep article but heres a sample:
More information.Skills and Advancement: Torchlight II's talent trees and skill systems may be tried-and-true, but they have such deep roots for a reason. Beyond that, the game's added a combo system based around "charges" that rewards you with buffs and special skills, so long as you don't take any detours from your warpath. Diablo III, on the other hand, scrapped traditional skills and talent trees altogether, opting instead for a slot system that essentially lets you pick and choose your skill loadout whenever you please. And then we have the Rune system, which lets you further modify a skill in multiple markedly different ways. Personally, I found that it encouraged variety and gave me options, but some players prefer Torchlight II's more old-fashioned approach.