Well, I just finished watching this. Luckily, I didn't spend money on it and merely borrowed a friend's copy. I would say it is a mixed bag.
The animation is better than some of the other efforts, but one area where they really messed up is by adding those cheekbone lines to Supes' face. It ages him dramatically and only serves to remind you that this isn't TAS that you are watching.
Doomsday is only in there for about 15 minutes, and his 'origin' is spouted by, of all things, Superman's robot buddy. It's not like the comic book character had much motivation to begin with, but he just shows up and starts killing. And he fucking kills everything in sight. I'm not one for 'edgy' takes on characters, but they really didn't hold much back with the violence. It's almost adolescent in nature. I can imagine all the teenagers are going to be impressed by the carnage, but to me it totally screams Late 80's Comics.
Thankfully, they didn't focus on the Reign of Superman aftermath (not literally, at least) but they did have Luthor's plot to clone Superman. This is where it gets really over-the-top homosexual in nature. The scene that wadew1 refers to is absolutely hilarious. Luthor is shirtless, beating on Clone Superman, when he straddles him and screams "Who's your daddy?!"
The best part, at least from a comedy standpoint, is when the Clone goes all evil. It's a bit like the Dark Peter sequence from SM3, but without the dancing. It features probably the darkest sequence I have seen in modern animation that is meant for children. SPOILERS: After Toyman has murdered a toddler, Clone Superman takes him from police custody, flies him to the top of the city, and lets him fall to his death by slamming into a police car. The next shot has most of his body covered in a bloody tarp.END SPOILER
The fights were pretty well done, but this still felt like something else entirely from what came before it.