I enjoyed Avatar. Was the story line "original" ?? Hardly. I could make many parallels with the story line. The English and the native Americans comes to mind pretty quickly. The CGI was pretty good.
As far as movies & TV shows injecting politics, Star Trek, TNG, Star Trek DS9, Star Trek Voyager, & Star Trek Enterprise were ALL rife with politics and social morals injected into them. Hell, District 9 had politics injected into it. I thought District 9 was a little too gory. I wouldn't let the little ones (pre-teens for sure) watch that one.