Warning spoilers ahead!!!
Honestly, this movie was pretty good. I love that they kept the old voice actors and characters, and I love the new animation. The story line was well written and really showed a realistic relationship between LB and CN. The villian are fantastic and there can be more than one at a time. They also have a new aspect on their powers and I love the idea that the miraculous have a mind of their own.
They do sing a lot, but the songs were good and important for the development of the characters.
By itself, when not compared to the tv show, the movie is very good. It's pretty much just season one but with darker themes and a reveal. I'm also glad they didn't add Lilah.
I do think things happened really fast, and I wish they showed more of the other characters. But considering it is a movie, I understand the pace. I hope there with be a second movie or at least something else that follows. Jeremy Zag did a excellent job and I'm glad that the characters aren't AS stupid/oblivious as they are in the show.