I've played Nicodem from time to time, and I think he does pretty well for himself in this edition. He can still summon pretty well with Canine Remains and Mortimer providing early corpse markers, and the Corpse Bloat upgrade really helps kick things off to a fast start. When you start looking to Wave 2, the Dismember trigger on Gaki and Philip being able to turn enemy scheme markers into corpses also help quite a bit.
Maniacal Laugh helps to get the zombie horde going once you've got some bodies on the ground, as it gives you an eight inch pulse of mindless zombies. The buffs he provides to undead within 6" of him are pretty amazing, so it's easy to get a little Nicodem "death bubble" going on.
Decay and Rigor Mortis are both great attacks, and Nicodem's upgrades let you adjust him in various ways, and I can see a use for all of them.
So, in summary, I think he's a very good master this time around, and Ressers certainly aren't a weaker faction this time around. All of the factions feel pretty evenly balanced, especially now that masters are being balanced one to one, and not on a faction to faction level.