For longer than I care to count the animation division of DC has been knocking out some incredible takes on their universe. Aided with great writing and good animation they often put the blockbuster live action movies to shame. All Star Superman is another home run for DC.
The story starts with Lex Luthor killing superman. Opps was that a spoiler? Well it was in the trailer so deal. Lex basically gives superman super cancer and Superman doesn't have long to live. So in true heroic fashion he tries to tie up loose ends. It is never that easy though, as various threats pop up. Also, Luther might have more planned for the Man of Steel.
One thing I like, no LOVE, about this film is that it whole heartedly embraces the weirdness of the silver age and updates it for today. A lot of the story is set around Superman's fortress of solitude and it is delightfully weird to an almost wonkaesque level. There's the key made of dwarf star matter, there's the baby star eater that superman feeds tiny suns that he makes on his cosmic anvil. There are all the superman robots keeping things tidy (maybe batman should by one to help Alfred). It really makes Superman fun.
The characters are all fun as well, but they also have a good emotional depth. Superman's goodbyes feel real and heartfelt. Lois and Jimmy were well realized. Even Lex had a lot more depth than usual. His hatred is what sets everything in motion, but behind that hatred is something else. A longing. Also, they made Clark Kent persona the most fun since the days of Chris Reeve.
The Animation is beautiful and has a subtle glow to it you don't generally see. The Action was great but not really the point of the film. It's the quieter scenes that best rendered.
In short, I say definitely give this a look even if you aren't a Superman fan.