Delpy and Bullock both did great work, and to suggest the former was just "doing her schtick" for a third time is to grossly undervalue what she did. In its own way, it's a unique performance as well, because name me another actor (well, besides Hawke) who got a chance to play the same character three times over two decades and show that character naturally developing and evolving and expanding each time. Sure, it's not the first time an actor went back to a character he'd originated a decade or two before (see Newman as Eddie Felson, Pacino as Corleone, Nicholson as Jake Gittes), but it might be the best - and, in any case, a very rare - example of an actor aging with and developing a character over multiple films and decades.
Anyway. Point is, ultimately great acting is great acting, regardless of what's involved, what's the process, and how original/"revolutionary" it is or isn't. It's also very much subjective.