With the final act, I didn't have an issue with the twists or runtime exactly, but...

(Spoilers)

I do think the film kind of lost Cruella's arc a little. The film seems designed to have her break bad at the end, up through her big monologue, but in the actual climax, all she does is get a murderer arrested. They bury Estella, but Cruella actually seems saner and on better terms with Horace at the end than she had been for the whole second half of the second act. When they ask Cruella what they're going to do now, her "I have some ideas" response was annoyingly evasive to me, because I honestly wasn't quite sure what they were going to do now. (Obvious tie-in aside, the post-credits scene didn't really clarify Cruella's mental state to me.) Ultimately, I feel like they hedged it a bit at the end, avoiding making her a full villain even though that's the logical conclusion of both the preceding movie and the original story.

I'd add in, though, for anyone reading this who hasn't watched it, that this is still a really good, fun movie that I'd recommend.