Yeah, Avatar is easily a must-see film.
Abriged: The film, has absolutely stunning CGI effects, although it has a rather cliched plot, it's really carried by the environment, the designs and the action, all of which add to make a pretty realistic science fiction movie.
Abridged (more): It's everything you expect, executed well.
Everything I told you, maybe a little less, can be backed up by watching the trailer. Go ahead, google it.