Warning: Lots of spoilers ahead: Upon reading the first article on Next Avengers (I believe it was Avengers Reborn at the time) I thought to myself "dear mercy, this is either going to be a cheap knockoff of Batman Beyond or the superhero version of Muppet Babies." There was no way in my mind that you could kill off the icons of Marvel Comics, replace them with children and still have a good cartoon. I was wrong! I also thought this was going to be like Spider-Man Unlimited or the 90's Avengers show. Thank goodness, I was wrong there as well.
The cartoon is something along the lines of the Marvel Action hour cartoons from the 90's, just with a better script and much better animation. In fact, having seen the cartoon, I would be more than willing to watch it as a cartoon series. Keep in mind, it is intended for a younger audience, but I think most Marvel fans will enjoy it.
Now, there are flaws. Mainly in that the beginning is done with quite a bit of exposition to get you up to speed on what has transpired in the Marvel U and where the heck these kids came from. I feel that Marvel could have taken an extra 15 minutes and given us a little more to go with than some static shots. But the story is told as a bedtime story to the Avengers' kids, and since it figures into the story later on, I suppose it is all right.
The only other thing that bothered me is that they never explained how Ultron gained that much power. The Avengers have already beaten him several times in the past. The only thing I could think of is maybe after years of being out of commission; the Avengers just couldn't cut it any more.
The kids themselves are pretty well adapted and are very close in persona to their "parents" while being individual enough to not seem like direct rip-offs of the original Avengers. In addition to this, they are also not as strong as their parents. This was what won me over. Marvel could have easily gone off the deep end and made these kids an ultra-powerful super group that every child should want a toy of. They played them off as kids with kid-like uncertainties and still developing skills, however, and it never felt like the kids were supposed to be better than the original avengers. They even needed help from the Hulk, which is a great scene. In the end, all of the kids are very likable, and are very Marvel-esquire.
The writers did good to keep this one just above Saturday morning cartoon level. There wasn't any really painful dialogue. Even Pym, who was supposed to be the annoying little kid of the bunch wasn't annoying enough to stop you from liking him.
The art was nice. The CG used wasn't too overly distracting, and the costume designs were cool and functional and futuristic (keeping with the theme). Iron Man and Hulk both looked good, as did Ultron. The people living below "Ultra City" look like something out of an anime (Origin and Nausicaa come to mind), and seem to serve no other purpose than to explain where Hawkeye's son has been, but it at least explains where the remaining humans have been. The look of the cartoon reminded me of Avatar in a way. Mainly because it has that 'not-quite-anime-but-definitely-influenced-by-it' style that Avatar uses. The animation is very smooth and the fight scenes are energetic and fun to watch. The character designs are nice and, once again, are very much in tune with Marvel. Personally, I liked James' getup. Very retro.
The music was extremely similar to Ultimate Avengers, along with the slightly Danny Elfman-ish theme (which reminded me of the Batman & Robin theme from '97). It fit though, and the music was actually fairly well placed for a direct to DVD movie. The sound effects were also well played, and nothing sounded out of place or distracting.
Voice acting was very good. This is particularly impressive given the age of the voice cast. They all blended very well with each other and fit the characters nicely.
Overall, I think Next Avengers is a very good cartoon and definitely one that kids and Marvel fans will find cool and I recommend it! I really do hope they make more! -Matt