A young boy watches his mother die of cancer in front of him when he is about eleven. Then, he gets pulled into a hovering spaceship and the rest of the movie is a fun, humorous, imaginative (Star Wars/new Star Trek) ride through deep space. If this sounds like two different movies, that is because one of the movie's strengths is that it combines emotion and the "out there" space elements flawlessly. Too much humor and the movie about the kid from the 80's who grows up in space and hangs out with the talking raccoon and his "houseplant/muscle" will seem silly. Too much seriousness and it would also seem silly because of the talking raccoon and humanoid tree person. This well-written movie balances all that really well. Yes, you don't have to know anything about these characters before you go. I have seen all the Marvel/Avengers movies, but I never read GOTG comic books, so I went into this movie blind myself, despite being a Marvel fan. AND...I am also a fan of "old-school" science fiction from the 50's and 60's, which this movie nods to considerably.
You have have Peter Quill (played by Chris Pratt), the adult version of the above-mentioned kid who got pulled into a spaceship after his mother dies. He is a Han Solo type, a criminal with more quippy, contemporary references (well, 80's...kids still know some of that stuff, right?) than Han Solo because he comes from Earth. Yes, he is in a galaxy far, far away, but his cassette tape walkman and the 70's-80's music that fills the soundtrack (that his mother gave him) will remind you that homeboy is one of us. He is a smuggler-type with a high-tech mask and a blaster who calls himself Star-Lord (because this is a "superhero" movie, kinda...and someone can't be just Peter Quill). When his latest score (an orb that he wants to sell to a Collector), puts him in hot water with some baddies, including the Kree Empire, a villian named Ronan and Thanos (the purple dude from the closing credits of 'The Avengers'), he ends up in a space station/jail where he meets the green-skinned, kick-butt female Gamora (Thanos' estranged daughter) and Rocket (played by Bradley Cooper), a genetically modified raccoon who is basically Dirty Harry in a raccoon's body (in space). Rocket and Peter are hilarious together, as is Rocket's tree creature friend Groot (Vin Diesel's surprisingly LEAST wooden performance), who can only say "I am Groot" in varying pitches, depending on his mood/sentiment. They also meet Drax an alien musclehead, who has a grudge against Ronan. Between wanting money for the mysterious orb and revenge against Ronan, the five form a team and escape from prison (in a brilliant scene) to have space adventures. Gamora is a great character, played by a great actress (Zoe Saldana) and she and Peter get close. Rocket and Groot (who could be "just" the comic relief) make you feel for them and laugh with them (and care about them when they fight at the end). Every character is well-fleshed out, even if their backstories are only quickly explained (kind of like the Avengers, but those characters had their own movies). Still, very well-done.
Marvel comic book fans will be happy to learn that this orb contains the second "Infinity stone" that we have seen in a Marvel movie. Marvel hipsters already know that the round thing in Loki's staff in 'The Avengers' is the first one and there are five and Thanos wants them. Speaking of Marvel hipsters, stay for the after-credits scene at the end. The most "Marvel hipster" reference I have ever seen in one of these things...and funny if you get it.
4 Infinity Stones out of 5.