Just an absolute blast all the way through. I always felt like the first two had so much wasted potential as these movies have a great mythology and world to explore but it never quite got there. These are what these movies should have been: fun comic book fantasy/sci-fi throwbacks with that never takes itself too seriously. For the first time, Thor and Loki feel like brothers and their dynamic is actually one of the best things about this. Thor himself is actually now at his most fun than ever before. Hemsworth plays him as that cool, sweet, fun jock who you would love to just hang out with. Hemsworth really excels at comedy and these kind of roles so he nails it. Bruce Banner was fun to have on the screen too with Ruffalo and Hemsworth playing it almost like a buddy cop movie. The supporting cast is cool too with Cate Blanchett, Taika Waititi, and Jeff Goldblum all bringing their own quirkiness to this world. But Tessa Thompson was the stand out. A lot have called her the "Han Solo" of the movie and it is easy to see why. She's badass, cool, smooth, funny, and you can't help but wish she was on screen every time. Thompson needs more starring roles and this film shows why.
If I have a complaint about this it's it still has the occasional trappings of the Marvel formula which feels weird against the other newer formula at play here. The villain's motivation is the same as others and it has a lot of the same story beats and pacing the other Marvel movies have. But it is still very much worth your attention. Most of that praise should be given to Waititi who understands what kind of movie this should be. He balances the tone perfectly and makes for one of the most fun Marvel movies to date. More in likely too, this will be the one with the most replay value. Go see this and just have a good time.
P.S. This has a great soundtrack too.