I think Iron Man had one of the best stingers of the movies I have seen that had stingers. If only because...
Nick Fury shows up and tells Tony Stark about the Avengers initiative. So, basically, Marvel is foreshadowing an Avengers movie as soon as they get a few other related-movies (Thor, The Incredible Hulk, Nick Fury) released.
As for my thoughts about the movie as a whole... when it comes to modern super hero movies, I think I liked this one more than Batman Begins and Spider-Man 1, which is really saying something because both of those movies were fantastic as well.
If you can still see it in theaters, you should try to, but otherwise rent the movie when it comes out. Or buy it, I don't think it would be a bad purchase.