And, well, I have to toss this out there because it made me laugh.
Sure, it plays out as one of Alice's visions, but it's not at all a vision that's without detail and unclear - it's extremely clear and marvelously detailed. I had seen the other movies, and really felt sorta "Meh" about them for the most part, but this served as a real payoff for me - not a "copout" at all; not be a longshot.
Yeah, the ending wasn't cop-out and not at all analogous to the "Emperor having a day dream" thing posted above. Essentially this was the movie being able to have it's cake and eat it too, it was able to have a big climatic battle that was exciting and action-packed (something you need in a movie) and also have the "true ending" of the movies at the same time. And I think they did it very, very well. The movie also has plenty of tongue-in-cheek moments in it where it's obviously playing with itself in being self-aware of what it is. (The director of this movie and the last one is no slouch by any means.) The scene between Jacob and Mustache-Dad where Jacob reveals himself was hilarious and playing with the "shirtless hot boy" trope the movie's become known for when it comes to fan-girls and Twilight Moms.
Actually a fun, surprising, movie.