I do not think I've watched trailers for the movie, or if I did I forgot them, so I went in without much of expectations. Especially since do not remember a good iteration of the franchise since 2012 TV series, which I enjoyed quite a lot. I think if I had more expectations I would be even more disappointed.
The art style is definitely interesting, and I think it does work here. I also like, that they continue giving the turtles different bodies, although I am not sure Mikey needs to be this small. I am also not so sure about voice casting, especially for Donnie. But what made me drop this... Was Splinter.
I was a fan of Jackie Chan movies when I was a kid. I watched some of them like a dozen of times, so no, my problem is definitely not with him, although, I still think he is not the best fit for Splinter. My problem is that Splinter is no longer ex-human, and not a ex-samurai. This has been a very huuuuge plot point in all the franchise iterations that I remember, and I'd say it was a crucial one.
Splinter was not just wise, he knew of the cruelty humans are capable of, and that's why he was teaching his kids not only to fight, but to also be better. He has known pain, he has known loss, and that made him such a good teacher for the turtles. But this new "Splinter" has nothing of that. He only has paranoia. It's justified, yes, but does that give him enough wisdom, that he can impart to the turtles? No. He does not even have enough knowledge to teach them how to fight.
2012 TV show was really good at showing us where the Splinter teachings were coming from, and we actually saw the turtles maturing over time (yes, even Mickey). Arguably even better than the 80-90s series, which was quite a bit more "cartoony" as far as I remember. This was the core of the show.
This movie, though... If they would have dropped the "Ninja" from the title, and treated it as "movie about mutant turtles, that's kind of inspired by previous works, but not really the same" - that probably would have been fine. But as is - no. Just "no".