For me anyway. My problem with this book, is that it is essentially a conversion of the Chaosium's old Elric! game to the d20 (Dungeons & Dragons 3rd edition) rules. That's not bad in of itself, it's just that the conversion seems to have been a rather shoddy and rushed job. Just the bare minimum was changed from the original Elric game, the various sub systems (like critical hits and allegiance) were left pretty much untouched.
Basically, the only stuff added for d20 is a handful of feats, and a new race (Half Melnibonean).
On the other hand, because it's basically the same as the Elric! RPG, only for d20, that means it's an excellent book, like the original Elric! rulebook. It's well written, and gives a very good (IMHO) overview of the Elric Saga, a decent (but not great) overview of Elric's original world, as well as descriptions of characters and critters from the books.
Still, even then it's got a couple problems. One of the common things in the Elric (and other Eternal Champion) novels is the concept of traveling to other planes. Elric does it a lot, yet it's not mentioned at all in this product. It's also got a really misleading section entitled 'Mass Combats', which just tells you to buy a miniatures game of your choice at a gaming store.
So, all in all, it's a very good book, but somewhat disappointing if you already have the Elric! RPG. I'd give it a 5 for people who don't have it, and a 1 for those that do.