Gabe Rodríguez’s review published on Letterboxd:
The third THOR film goes in a very different direction from the first two, feeling more like a GUARDIANS OF THE GALAXY entry in terms of its comedy, bright colors, FLASH GORGON camp, and self-aware humor. Everything about it is fun and you can tell the entire cast is having a good time.
The main flaw for me is that the film feels like multiple storylines being smushed together. The first act feels like a quick connect-the-dots revamp that quickly ties all the loose ends between the end of THE DARK WORLD, AGE OF ULTRON, and DOCTOR STRANGE (you could have cut Benedict Cumberbatch's cameo and not really hurt anything). It's not until quite a while in that Hela (Cate Blanchett) is introduced and her plan to take over Asgard is set in motion, and so the movie really begins. But Hela then gets sidelined as almost the entire middle act of the movie takes place on the planet Sakaar, where Thor, along with Loki and the Hulk, must take on another villain, the Grandmaster (Jeff Goldblum, having a little too much fun).
I feel like the Sakaar storyline should have been its own movie while the Hela plotline should have been another. And yes, even as someone who's not a comic book fan, I'm vaguely aware that Sakaar is taken from the famous PLANET HULK storyline. I can't comment on whether or not this is a faithful adaptation; all I can say is that Sakaar is an interesting place and the entire time Thor is there, you barely care about what's happening back on Asgard. Jeff Goldblum and Cate Blanchett are both equally good villains and each really deserved to get their own movie. It really does feel like a shame that Hela barely does anything until the third act.
But I guess the main audience for this movie is not really concerned with the plot. In terms of just overall aesthetics, there's no denying the movie has the right amount of Saturday morning cartoon fun, right down to even having Clancy Brown be the voice of one of the cartoon bad guys. Of the three THOR movies, this is definitely the one that feels the most like a comic book in tone.
Chris Hemsworth, Tom Hiddleston, Mark Ruffalo, Tessa Thompson, and Idris Elba are all good, but perhaps the big surprise is Cate Blanchett, playing what is basically Evil Galadriel. Her scenes always feel like LORD OF THE RINGS-lite.
THOR: RAGNAROK is a huge step up from THE DARK WORLD. It ultimately lacks the emotional weight and character moments that made the GUARDIANS OF THE GALAXY films so good, but nonetheless, it's a satisfying installment in the Marvel Cinematic Universe.