Empire Online brings us the following Q&A:
How are you going to avoid the usual sequel pitfalls? Often they become all about the villain at the expense of the stars.
"Yes, that always makes me cranky. I'm very excited about the villain, and have a lot to say about him. But if you watch my shows, the one thing I've never been very good at is guest stars, because I've always been interested in the ensemble. With The Avengers, I'm still most fascinated by them."
(If you're incredibly keen on this sort of thing, you'll have noticed Joss says "him" there, which means the villain is not female. In fact, it's most likely to be male.)
"The other thing is, you don't try to top it," Whedon adds. "I know I will never make a moment as pleasing in a film as Hulk and Loki. You can't chase that dragon. If you try to do exactly the same thing, the chances you're going to do it better are very slim, and the only reason for me to devote three years to making another Avengers movie is the hope of making a better one."The film is scheduled to hit theaters on 01 May 2015.