Fortunately, the movie has far, far more going on than plot and character development. the world of Pandora is a wonderous place, and the movie puts you there. It's truly inventive and interesting, and I can't really say that about many movies these days. It has incredible atmosphere and, yes, even craft. It's an extremely well done movie for what it sets out to do.
This is the kind of thing I'd bring my little brother to watch. Hell, I'd say that a more complicated and convoluted plot is the last thing Avatar needed, considering its main objective - a fun piece of entertainment that takes you away from our world and into another.