Re the Ult Spidey cartoon: I don't find the chibi moments too distracting, but I'm a little concerned that it's been three episodes already and we still haven't learned much about the characters except Peter. If you ever watched Teen Titans, they jammed a whole lot of character development and backstory in the first few episodes, while still having kick-ass fight scenes. Maybe it's just my DC bias at work, but I'm slightly concerned that an Avengers cartoon following the Ult Spidey model will be thin on character and relationship development.

That said, I don't think it's impossible to do character development just because you're not doing really long plot-arcs. The DCAU had plenty of one-shot eps, as well as really fantastic character/relationship development. (Of course, Justice League was entirely 2-parter eps, a full 42 minutes per story, not to mention 3-parter premieres and finales.)

My particular worry is that a new Avengers cartoon won't have Wasp in it. We might get Natasha on the team, if they're basing it on the movies, but probably no Jan or Hank.