I haven't finished it yet (hence why I'm putting my thoughts here and not the review thread) but I imagine my impressions won't change at this point; playing Guardians of the Galaxy and I've a very positive but nevertheless mixed feeling.
On the one hand it's basically a Marvel take on the Uncharted formula of cinematic 3rd person action adventure, I think a lot of reviews out there were overselling it as something it's not.
My only impression of GotG before this game is the MCU movies, but I'm sure many others are the same, and with that said I think it's a really good adaptation.
Gamora and Star-Lord are different but still enjoyable in their own ways (I think I actually prefer this Gamora!), whereas Drax, Groot and Rocket are pitch perfect impersonations to their movie counterparts and the team dynamics that come with it.
I think the reason the game is getting such aplomb is simply that it's a really good GotG adventure, the story is the main appeal here; it's a good comic book/tv series style story and if you're a fan of the characters then it's worth a play for this.
That said, I can't get it out of my head at this point (I'm at chapter 13) that the game, given it's surprisingly lengthy, is quite repetitive.
It's mostly either exploring environments in a pseudo Uncharted kind of fashion, which is all fairly inconsequential really. Or it's the combat, which while satisfactory, and there are plenty of options to play with, every encounter plays out basically the same, which over a game that's pushing the 15-20 hrs mark is just too much.
I think game needs to be either shorter or the combat had to be ultimately more complex. That said it's still wroth a playthrough for the story as its really strong.