I got necro to 25 last night, felt a bit chaotic compared to my frost sorc hydra build as even though I had 7 skellies and 5 mages in my army, they would all just attack whatever they felt like.
When butcher showed up it became a struggle to kill him because he's capable of killing my summons and you can't really stop to summon more.
So far think I prefer the sorc feels more controlled, though hydra was pretty strong and it may get nerfed. I also had some of the same issues with the summons as I had with d2 necro, if they die you're kind of helpless to do much.