1) The movie is not that good, and thus is stuck in developmental hell as the producers continually push back the release date. (ie Dark Water, Against the Ropes, etc.)
2) The movie is probably pretty good, but whether it is good or not is really irrelevant, as the only reason that you're seeing a preview for it six months before it comes out is because it is what industry insiders call "highly anticipated". (Star Wars, Harry Potter, Spider-Man, etc.)
I just watched all 25 GI Joe PSAs. I love life.