I believe that the necromancer archetype has sadly fallen by the wayside in 4e, so i was naturally excited to find this PDF, however it has two or three things that need to be revised.
First there is the artwork, Most of it is pretty good (i especially enjoyed the image on the cover) but i'm not really sure that CGI art is appropriate for a role playing game supplement.
The second thing that kind of bothered me was the whole "Davey Jones" undead pirate thing. The concept just seems silly sitting next to the other stuff in the book, like it was tacked on in the editing process. I would seriously just cut the idea out of the book altogether.
Some of the wording in the implements section is a bit confusing, but if you just assume normal implement rules,hybrid implements rules and ignore the hybrid talent option everything should work out fine.
The class IS presented as a half class, or a multiclass option, but since I've always considered necromancer an offshoot of a wizard i dont really see this as a problem. If you want a full class necromancer just Hybrid the necromancer with a wizard and reflavor some of the wizard spells. (or ,even better, if you own heroes of shadow choose some wizard spells from that)
I think that this is a decent book that has a few faults, but has some great ideas. The class seems balanced, the powers look really neat, and (with one exception) the paragon classes sound really cool. Like i said you have to change some of the wording in the implement sections but all in all it seems to be a very playable and balanced class.