I don't remember talking about this one after it released, but I just re-watched it and was reminded why it's one of my favorite Marvel movies.
The movie picks up after the events of Guardians of the Galaxy Vol. 2 and Infinity War/Endgame. It touches quite a bit on Peter's loss of "his" Gamora and Kraglin taking over for Yondu, but the main story revolves around Rocket and his past.
You learn about how Rocket became Rocket. Essentially abuse and experimentation at the hands of an egomaniac called The High Evolutionary, a geneticist seeking to create the "perfect" world at any cost.
Like the previous installments of the Guardians trilogy, this one perfectly touches on found family. While the group may not be perfect, get on each others nerves, and a bunch of losers (folks who have lost stuff, in Peter Quill's words), they are there for each other. New to this story, though, is the lesson in letting go. Whether it's letting go of a loved one you thought you knew who turned out to be different, or letting your loved one move on to find themselves outside of the perception of others, or going back to your old life that you were ripped from and continued to run from.
It's obvious how special this story is to writer/director James Gunn. Both from the perspective of animal rights all throughout the film (a tough watch, but done well) and a more personal perspective. He has stated before that of the characters in the movies, Rocket is the one he relates to most. A heartbreaking fact after watching Vol 3.
This is an amazing ending to a well-done trilogy. It's James Gunn at his best. One of the cornerstones to his movies, for me, is his understanding of characters. I went into the first Guardians movie expecting Rocket and Groot to be throw away characters, meant for toy sales. They ended up being the heart of the movie. And Rocket, the heart of the series as a whole.
I'm sure if you watch Marvel/comic book movies, you've most likely seen this. I do think this is a great series for those who aren't as into the genre. It tells very human stories through these non-human (in most cases) characters. A lot of the emotions they go through throughout are relatable. So, if you're looking to dip your toes into the genre, I highly recommend the full Guardians of the Galaxy trilogy.