Dan Pendleton’s review published on Letterboxd:
What a fun ride Guardians of the Galaxy is! I knew nothing of the comic books beforehand so had no idea what to expect, but this is a sci-fi comedy and not like the other Marvel movies. It's really refreshing to see something completely different.
James Gunn has hit the tone perfectly, not taking the story too seriously and allowing all cast to really play and enjoy themselves. There wasn't a single person onscreen that I didn't enjoy watching.
There is definite room for a Guardians of the Galaxy sequel and I'll be first in line to see it. That being said, I'm not sure how well these characters would interact with the larger Marvel Cinematic Universe. Of course there are a few links already (such as Thanos, The Collector, and the infinity stones) but I'm not convinced the Guardians would merge seamlessly with our established superheroes; it would be too much of a genre clash. I'm not sure if that's even Marvel's plan but I think the Guardians will be best kept mostly within their own storylines.
I saw this in IMAX 3D but I wish I'd seen a 2D version. I don't know if it was just a problem with the showing I saw but I felt that some of the 3D got a bit lazy towards the end, mostly during the air battle. There was also one shot of Drax where the depth of 3D went all over the place and it looked like he was really, really 'happy' to be there, if you get what I mean.
Overall, Guardians of the Galaxy is one of the most entertaining movies you'll see this summer and has opened the gates to more different Marvel movies.