It's pretty much a modern version of Super Friends, so don't expect some kind of deep story or anything like that. It's overall a fun but very predictable and formulaic movie. It's not as dumb as Super Friends could get in general but there's one scene that's so idiotic I can't help but love it: Some members of the Legion of Doom have been sent to the past to stop Jonathan and Martha Kent from raising Superman, so Solomon Grundy and Cheetah take the clothes from two farmers (which are heavily implied to have been killed) to fool them into thinking the baby they just found in a spaceship is theirs! Even dumber, it's later also implied that Toyman killed the Kents anyway so the whole thing was completely pointless. It's obvious they wanted to make the movie kid-friendly and keep the deaths off-camera but it's still so stupid you can't help but love the whole thing.
@darknightspideyfanboy: You totally should, it's a pretty fun movie (and despite what I said about the plot being predictable the ending is a bit unexpected). Besides, it's worth it for that scene alone (and later on the Legion of Doom and Flash, Aquaman and Cyborg fight over baby Superman in a pretty funny slapstick sequence).