R/T currently clocking this at 77%, the lowest of the 3 movies.
After reading the negative reviews, it seems pretty clear that one or 2 things is going on with each of these naysayers. One is that they simply don't truly "get" these movies and/or two, they were simply expecting something else. One critic bitched about some stabs at animal cruelty, which is in fact, foundational to Rocket's existence. Another complained about the movie's runtime..... well, 2 1/2 hours is certainly not an exceptionally long MCU movie (Endgame 3:01, Wakanda Froever 2:47, Eternals 2:36 and several others in the 2:20's) and if Gunn says it's all stuff and no fluff, I'll take his word for it, methinks.
I haven't actually seen the film yet, but based on the trailers, and there's a bunch of them, GOTG 3 looks to be a helluva good time and fitting sendoff to the team. I'll know for sure shortly....