I liked the movie overall, but I definitely would not place it in any "top movies" list.
Some fans will no doubt eat me alive for saying this, but I've always hated Whedon's dialogue. It sounds too "teeny," and sarcastic one-liners just aren't my style of humor. In addition, it often feels to me like every characters speaks with the same mouth - they crack the same jokes, in the same kind of way, and use the same vernacular despite VASTLY different backgrounds. He can only write dialogue for two characters: one with a sense of humor, and one without. And that has always bothered
me in all of his projects, not just this one.
But like I said, the movie was good. It kept my attention. I felt the dialogue often pulled me out of the story and ruined the verisimilitude, but I would still recommend it.