go see it!! also theres more to the movie then just ultron... theres a reason for the avengers fighting each other in the trailers. Also infinity stone and gauntlet after credits its all going to intertwine.. fantastic four, avengers, gaurdians, xmen... the infinity gauntlet Thanatos, mandarin etc...
They literally have dozens of other titles to merge into this. I'm sure they don't actually *need* Xmen or FF
Marvel also supposedly has the rights to put Spider-man in movies now, so I expect to see him in the next Avengers as long as nothing falls through.
My issue with it was less with the plot and more with the pacing. I never thought I'd want a movie to have less jokes. Vision was a bit out there, but you do have to remember these are movies from comic books. The only twistier plot lines you'll find are in soap operas. First Avengers was definitely better.
Only one I found genuinely funny was Spoiler "You and Banner better not be playing hide the zucchini.'" /agree