I agree with all the reviews here. This is a VERY good animated movie from MARVEL Studios distributed thru Lions Gate.
I recently rewatched the first one to refresh my memory on its story in preparation for this second one. I'm glad I did, because these two movies are indeed sequels. Well, the second is a sequel to the first...you know what I mean. Anyway...
First of all, I really did this kind of animation. A bit more realistic than Bruce Timm's Justice League style, but also more comic booky-looking. By that I mean the animation looks like something you'd see in a average comic book THESE days. You could freeze-frame any scene in these Ultimate flms and it'd look like a comic book frame. Which is good.
Secondly, I love the Ultimates take on the characters. As I'm not a comic book reader, I could care less about continuity at this point, so for this series to "throw out" any established continuity is a good thing for new viewers. My favorite character by far is Iron Man. Love his voice and his animation. The aid of CG is a good thing for his character. Especially when he dawns the War Machine suit, after Iron Man v6.2 is destroyed.
Thirdly, I love the level of violence. This is a very mature animated film. There's blood and people die. The battle scenes in this movie are quite good. Very dramatic and breath taking, if you will. And as you might have gathered from other reviews, this series takes a page from Tom Cruise's "War of the Worlds", and the 3-part pilot of Justice League, "Secret Origins".
Also, as you may have guessed, there's a hilarious gag reel included with this disc which basically features clips from the original movie, but with different voice overs (with newly animated mouth movements). But of course with Iron Man not having a visible mouth, they use a long running gag through-out the gag reel that Tony Stark runs and promotes his BBQ Rib joint. You gotta see it to believe it! Very funny stuff.
To conclude, if you're at all interested in seeing the first couple of Ultimate Avenger comic books brought to life through these two animated features, I highly suggest you pick these up. If this was made into a long running weekly series, it'd surely give the excellent Justice League a run for its money.