The consensus is that the third movie in virtually any superhero franchise (which has gotten that far) is weaker than its predecessors. Superman III, Spider-man 3, X3, Batman Forever, Blade Trinity.
Indeed, nearly all third movies in a trilogy end up being the weakest, from Godfather III, to Return of the Jedi. Only Bourne and Die Hard break the jinx (well, you could also include Revenge of the Sith and some might include Indiana Jones 3).
While it is the general critical consensus (and my opinion as well) that
Batman Forever &
X-Men: The Last Stand were the weakest of the 1st 3, that's not the financial result.
X-Men: The Last Stand made far more than either of the 1st 2.
Batman Forever didn't come close to
Batman (1989) but was a marked improvement over
Batman Returns (a Tim Burton masterpiece that just gets better with age).
As for other threequels, I hated
The Bourne Ultimatum and
Die Hard with a Vengeance was my least favorite of the 4
Die Hards.
There are some threequels that I feel end up being the best in the series, or close to it. Examples:
Star Wars: Revenge of the Sith. Although, it's not like the other 2 prequels were very tough acts to follow anyway.
Indiana Jones & the Last Crusade. IMO, the 1st 3 are almost always in equal position to capture 1st place. But when it comes to fun & character development, you can't beat
The Last Crusade.
Back to the Future, Part III. Granted, it probably would end up in 3rd place if I ranked the trilogy. But each movie carries a different element.
Part I is the funniest.
Part II is the most exciting.
Part III has the most heart.
Everyone gets so pissed when they reboot a property instead of making a continuation yet this gets thumbs up? Interesting.
I suppose it's because there have already been so many other different interpretations of
Batman. There is no unified continuity or even unified style. The Nolan movies are different from the Burton movies are different from the animated series is different from the Adam West TV series. Even the Joel Schumacher movies, which seem intended to be direct follow-ups to the Tim Burton movies and use some of the same actors, still feel like they are a very separate thing.
So unless Nolan's successors make a concerted effort and manage to get Christian Bale & Michael Caine back, it's a foregone conclusion that the post-Nolan movies are going to be a completely different thing. With that in mind, there's no reason to bend over backwards to keep the franchise going. This is a rare chance to firmly end an iconic, very profitable film franchise, or at least one interpretation of it.
It was a very smart move on Nolan's part to do this. Unlike in the Spiderman movies, where Peter Parker makes absolutely no attempt to disguise his voice. The scene in Spiderman II where he saves his aunt makes no sense. This woman is his mother for all intents and purposes, and yet she doesn't recognize her "son's" voice when Spiderman speaks to her?
I was always under the impression that Aunt May knew pretty early on that Peter was Spider-Man. She was just playing coy.