This is definatly a great supplement, but that is all it is... a supplement. This book is not the be all end all campaign creator. I find this book, enjoyable to read (I admire the necromancer class) and a very excellent addition to building mysterious and dangerous necromancer NPC's (this book includes an suggested necromancer dragon!).
With this book you can make an NPC to scare your players away, and show them just how powerful the dark arts really can be. The warned, this book is mainly for the DM for creating NPC's. It is not meant to be used as a Player "Class" option. However, I would possible let a player create one of these unique necromancer kits in the right setting.
A must have for magic user freaks, and a DM looking to add a twist to their adventure.