Not all that fond of their current plan to have them simply do hit point damage. It's basically no different than swinging a sword and doing damage. In our campaign, they drain Con. The Con damage isn't permanent assuming they are not killed from the draining, but it also doesn't come back quickly either. Depending on the power of the undead in question, Con is restored anywhere from 1 point every few days to 1 point a week. This makes them truly scary while not having them destroy your character with level drains. Hit Point drains that are gotten back after a rest sounds boring. All that will accomplish is that if a few people get drained, everyone will just declare they are going to hole up and take a rest and get their Hit Points back.
All in all, I'm not impressed with their new version so far.
