This is not a BAD movie. It has some real humor (courtesy of Alan Tudyk, whose K-2S0 is pretty much Doug Adams' Marvin retooled as a combat bot, and Donnie Yen, as a blind almost-Jedi), and there are some truly magical scenes. But the characters are thin and the plot is improbable even by the extremely loose standards of the Star Wars franchise. In a year that gave us a creditable remake of "The Magificent Seven", a movie that mostly exists to set up a string of heroic last stand sequences just seems kind of flat.
This is the fifth Star Wars movie that I have walked into hoping that something will rekindle the magic, and give me an excuse to forgive the franchise for the stupidity and betrayal that was "Jedi", all those years ago. This isn't a BAD movie; it is the third or fourth best in the franchise. But it did not begin pay off my now forlorn hope, and it gave me reason to believe that nothing ever will.
On a positive note, this movie DID deal with a long-standing fannish, "Why did they...?" question about the design of the Death Star.