I'm new so excuse me if I say or do anything stupid. I really only joined because I saw Winter's Necromancer class. Anyway I have been playing this class and I am now at level 4, so far it seems pretty balanced. I have to say I have little complaints, but I do have some suggestions.
The Lances of blood were a bit overpowered, however I think I may have read the power wrong. I was stacking damage against one opponent, by sacrificing more health, and it seemed way to strong for a level 1 daily, I was dishing 200 damage at level one. Now I realize that sacking extra health only let's you hit more enemies, that should probably be made a bit clearer.
Some of the guys I was playing with suggested the idea of powers focused around disperse the Fleeing soul, so instead of using it to heal youself you can channel the lifeforce of a slain enemy into powerful attacks, and buffs.
Definately design some Necromancy based rituals, it would be really cool if we had some more. Necromancy based artifacts, alchemical formulas, and other items would be good.
Maybe some bonuses to death based rituals, for instance lowering the DC, have the cost, maybe use one or two Necromancy based rituals a day for free.
Maybe some variations on the Shadow Familiar.
My DM said that feats and such applying to wizards, such as expanded spellbook would also apply to any class whose powers are designated as spells, so that would also inculde the Necromancer.
Just some ideas, however I feel that for the most part the Heroic tier is successful.