Tell me, is that mod worth it?
I seems kinda complex.
I don't really want to clog my game up.
Yeah, it's definitely worth it.
It adds lots of cool variations to all creatures (a zombie Imperial Guard?!) and completely new things such as bats or giant spiders, or a skeleton army that works together to kill you.
When used together with Creature Intensity (more creatures! creatures travel in packs! a school of 3-4 slaughterfish! a pack of wolves!) Enhanced Weather, Enhanced Water, and Natural Environments (which adds ambient insects and birds) this makes an epic world that has a lot more in it than vanilla Oblivion.