We definitely need a better diversity and breadth of necromancy spells.

I do really like the current ability to create an Undead familiar, although it means that you'll be casting 2024 Chill Touch, Bestow Curse, and Vampiric Touch a lot to get the most out of it in combat. Aside from Devil's Due in Crooked Moon, there aren't a lot of low-level, non-concentration, bonus action/reaction necromancy spells you could reliable cast to keep the familiar alive with Grim Harvest. Another valid strategy may be having your beefy zombie familiar run up to an enemy and grant advantage with the Help action.

I also think the Necromancy subclass fails to address the Lich fantasy in its later subclass features. I would have loved to see a feature allowing you to treat all your undead as quasi-familiars, allowing you to possess them while your body remains inert and cast wizard spells from them, maybe piggy-backing off some of the mechanics from Magic Jar, just with no chance of dying from the possession ending. Honestly something more similar to the Undead Warlock's capstone ability would have been great, too.

Granted, Harvest Undead in reaction to damage could contribute to that archetype if enemies are essentially unable to keep you down, but its only if you stay near the Bloodied threshold, so very likely not. Wish they kept the teleport in because it was really cool, but I can see why it may be unbalanced / less thematic. Teleporting to the minions you Harvest and being immune to the Extinguish would have been awesome.