If you leave this movie without an 80's anthem stuck in your head, you're doing something wrong. The key to enjoying this movie is to not take it too seriously, brush up on your 80's pop culture, and embrace the cheese as fully as you can.
When we first meet Peter Quill, aka Star-lord, he is mysteriously abducted by alien spacecraft after watching his mother quietly pass away. Fast forward a few yeas, Quill is a music-loving, sacred grounds-desecrating artifact thief. Think of him as a cross between Han Solo and Captain Jack Sparrow, with a dash of Indiana Jones, and you'll have it about right. Despite having been abducted by aliens in the middle of his grief from losing his mother, and then raised by a rogue band of miscreants who reportedly wanted to eat him, Quill isn't a tortured hero with deep emotional baggage, which I found extremely refreshing. Not only would such an archetype be painfully out of place in this movie's tone, it would have rendered Quill's entire devil-may-care attitude a complete farce. Did Han Solo mope about his life as a smuggler and the enemies out to get him? Of course not. Quill is a welcome return to that Han Solo style of anti-hero: scoundrel, but not without a heart (as shown by his attachment to his walk-man with the cassette of classic oldies. Yes, you read that right-- a guy who flies spaceships and steals artifacts from distant planets does so with a walk-man and a cassette tape).
Among the rest of the crew eventually dubbed "Guardians of the Galaxy" are Rocket and Groot-- arguably the most obscure members of this ragtag band. Rocket is a quick-talking, mischievous bounty-hunter of a raccoon with a tall pet tree as a bodyguard. Said tree can only say "I am Groot" with different inflections and expressions to communicate emotion. This is oddly more effective than you might think, actually. Meanwhile, Rocket has enough words for the both of them, and never holds back what he's thinking, no matter how tactless it may be. They're unlikely yet perfect partners, just like the team as a whole really.
Next up is the shapely Gamora-- the adopted daughter of Thanos. It turns out however, that she actually resents Thanos wiping out her entire family and then adopting her to be an assassin. For a big bad guy like Thanos, I'm not sure how that didn't cross his mind, but it's not that important. She's working for Ronan, but she's out to double-cross him too and make sure he never gets his hands on the infinity stone that Quill is carrying around. Meanwhile, teammate Drax is out for revenge on Ronan for the murder of his wife and daughter, which is a legitimate vendetta. What Drax lacks in quick smarts (or comprehension of sarcasm and metaphors), he makes up for in brute strength.
This crew of misfits make up the team Guardians of the Galaxy, and eventually they save an entire planet...on purpose! This is especially surprising when you consider that earlier in the movie they were about to hand over the infinity stone to The Collector--the sleezy pawnshop owner seen at the end of Thor 2. But in the inevitable moment when the team must decide to save their own skins, or fight an impossible foe, they do the right thing.
Guardians of the Galaxy is one of the few movies that actually does a decent job of walking the line between a sci-fi action movie and a spoof. It has too much of both sides to succeed as a representative of either genre, but the result of the even balance is deliberately cheesy, highly amusing piece of entertainment that glories in celebrating its own overdone moments. The success of this attitude can be largely attributed to the somewhat unknown source material, and lack of any major-name movie stars except in supporting roles. Without any major stars in the leading roles, and not many people familiar with the source material, expectations were ambiguous if not low. Yet this actually works to the movie's advantage, because despite its stupidity, it feels thoroughly genuine rather than forced.
I can think of no better way to conclude than to recall a sequence that perfectly captures the quirky spirit of the movie. After an ambitious and thrown-together prison break full of explosions and narrow escapes, Quill doubles back to retrieve some personal items while the others board the ship. Once they are on board and leaving the bay, someone asks "where's Quill?" No sooner has the question has been completed, that Drax looks theatrically to the side to see Quill zooming towards them with his jet-boots, hair rippling in the slow-motion splendor of absurdity against a galactic backdrop, complete with the classic song "Escape" accompanying his moment. It is the most perfect embrace of absolute cheese that doesn't take itself seriously, and doesn't get lazy.
And for those of you who didn't catch it, it's Howard the Duck.
I know. WHAT?!