So obviously some of the Marvel Animation guys got to attend the premiere, including my director. His thoughts:
"Okay. Age of Ultron. You know how people used to say Star Wars made them dizzy back in the 70s, because it was so jam-packed with stuff? And then The Matrix in the 90s? This is that movie for the 10's. It feels like one of those anime compilation films, with 10 episodes or so edited down into a feature. It moves and jumps so fast, you feel like something was skipped over. It could very easily expand up to a TV mini-series with the sheer amount of stuff going on.
It doesn't have the same thrill as the previous film, which derived from all the characters interacting for the first time, but replaces it with non-stop momentum. Casual viewers may find it exhausting and frustrating. But if Marvel has already won you over, you're going enjoy coming back to this one and decompressing it a little further with each viewing.
That right there is a qualified thumbs-up. I think you need to be a pre-sold fan to get the most out of it. Fortunately for Marvel, there are a lot of pre-sold fans ready and waiting."