The book's final 'real' monster: it's only some animals and vermin from here on!
One could almost expect zombies to be semi-reasonable. After all, skeletons got +1 LA in a few select cases, and these guys are basically the same right?
Sadly, not only are zombies worse chassis-wise (ability penalty where skeletons don't get one, worse DR, worse bonus feat), they also have the horrible Single Actions Only trait (hope you didn't plan on casting spells and moving in one round, or making full attacks).
As if that's not enough punishment yet, zombies also lack a skeleton's potential to start without RHD. Zombies have double the RHD of the base creature, meaning their players will always start with at least two worthless undead hit dice.
Even with the mindlessness handwaved, I just can't assign anything other than -0 LA here. I'm sure people will agree.