I thought this movie was a phenomenal adaptation of the graphic novel. Now, while I think Frank Miller's Dark Knight Returns is an important step in maturing the comic book medium and the superhero genre, I think, comparing it to the stages of man's maturity, it's closer to the angry teenage years and that Miller himself is no longer relevant. However, wow, what a great two-parter! Really intense action, and I love the voice work. I'll agree with Ed in his review that part two felt better than part one because it concluded everything that was set up. Superman and Joker were the foils Batman needed in this (whereas in the first part, it was mostly about his decision to come out of retirement), and the ending was much needed (for me anyway) after the way Nolan ended his take on Batman (not that I minded what he did, I just liked this better).
I won't say this is without its flaws, though. While the Tunnel of Love stuff was appropriately brutal, I don't know how good it is for rewatch considering I prefer my Batman fight scenes to be a bit less...graphic. It was great in the context of the movie, though, just not my favorite animated action from Batman.
I did like the violence, though . Joker being allowed to be bloodied with a Batarang in his eye was nice to see after how weak the previous films have been on violence. I think sending these films to the MMPA for rating is pretty dumb (it's direct to video shelf fluff, after all), but I'm surprised the film got away with this much violence after how clean the previous PG-13 films have been. Now, if only the next Superman film had some real grit in the battles...
I think by now, they dropped the delusion that Cartoon Network will be airing these movies, so there's no need to censor them for TV anymore, and they can just kinda go nuts now. Blood and swastikas for all! Okay, maybe not, but you get my point.
I did like the way the movie expanded and tipped the scales of that big final fight between Batman and Superman. The book was one of the definitive "Bat-god" moments, where the two are really facing off as equals. While Superman gets walloped pretty good in the movie, it really seemed to me that the movie exploits the argument that says Superman would pound the stuffing out of Batman in a fight. All of Batman's tricks may be whittling away at Superman, and few if any of them would work if Superman were at full strength, but even then I feel like Superman's holding back and Batman's only trying (and, for that matter, only able) to keep him pinned down long enough for Ollie to show up with the kryptonite arrow.
Yeah, Superman was definitely being curteous. He even allowed Bruce to pick out the time and place of their battle (rather than, ya know, HEAT VISION HIM ON THE SPOT)
There is also the symbolism in the animals that surround the pair. Superman gets an eagle, while Batman is interacting with a very wolf-like dog. Both are predators, but one works from the air and the other from the ground. Superman is also representing the United States as their agent. Batman is also working with a horse, which foreshadows the moment when Gotham is hit by the EMP.
And that poor mouse was Oliver. I liked the subtle way they mentioned Superman's assault on him.