I just picked it up yesterday. Although I haven't examined it in depth, there's a lot in there that I like, at least flavor-wise. They present 14 different variations of magic, each with a full 20-level alternate core class presented. I hate the generic wizard, and the specialist wizards aren't much better. This is how I wish WotC had handled arcane spell casters from the start. In my home brew, I may consider removing the wizard all together in favor of these classes. I especially like the fact that they are core classes, not prestige ones.
They also present a spell point system, which is basically an adaptation of the psionic rules to magic. They place some sensible limitations on it to make it balanced, though it complicates things a bit. There are also new feats, monster templates, spells, items, and a set of free form spell casting rules.
So far, I think it's pretty cool.
FM