The story centers around Star Lord, a self nicknamed scoundrel in the Indiana Jones and Han Solo mold. There's a magic McGuffin, an evil overlord working for an even more evil overlord. There are family rivalries, hidden family connections, revenge, comic style violence, self sacrifice and a huge battle during the climax of the movie.
What I liked most about this movie was the tone. Very light and fun the whole time. Star Lord dances, a lot.
It's great all around, but I wouldn't exactly say it's for everyone. If you are into the slow well acted dramas you might not get much out of this movie, but for everyone else who likes the big summer blockbuster or is into the Marvel Universe at all this is probably the best movie all year. Captain America: Winter Soldier and X-Men: DoFP are also good entries, more serious.