It was a good comic book movie, but not a good movie because they fit too many things inside and rushed it too much to catch up to Marvel.
They should have excluded the whole Doomsday part and focused on the main story of the movie...but I guess they needed Doomsday so that they could "kill" Superman for the plot. Hopefully the upcoming prequel (Batman solo movie) clears a few things up and give more details and information.