There were several good things about this product. It provides options for truly earth-shattering play, and there were some interesting concepts and well written descriptions in chapters one and two .
However, there were also several things about this product that could have been far better. First, this product is really best suited for very small groups with one or two players along with the story teller. The system does not support group play (where group is even 3 players with the story teller) well at all. It gives reasons why archmages do not gather and why they are likely to work at somewhat cross purposes even when nominally allies.
Moreover, the Imperium System provided in the final Appendix is deeply flawed and difficult to make work. To be fair, it states that these are optional rules in a game where all rules are optional. But they are nearly unworkable. The rules state that the Pax Arcana does not apply to Imperium, but these are precisely the things that it seems the Pax Arcana should apply to. More than that, they are exactly the kinds of things you would expect to gain notice from the Exarchs themselves who would move to stop them decisively.
This book is also deeply lacking. In a book that deals with powers that whose mere possession may breed hubris, it only very briefly touches on sins against wisdom (and one of those is not given any explanation). In particularly, it does not discuss the affects of pursuing Imperium on wisdom even though some of the suggested possible goals for Imperium seems like Sins against Wisdom 1. It does provide some example spells for spheres above rank 5, but far too few for my taste when those seem like they should be a major focus and where each rank should last for a substantial amount of time. It gives very short shrift to discussing how an archmage might create artifacts and the type they might create, though that is mentioned in other books repeatedly as something significant archmages do. It also only lightly touches on the kinds of favors an archmage may want from lesser mages and vice versa, though that is an excellent way to introduce archmages to a game. And for a supplement about archmages, it gives few suggestions as to how to create archmage characters for players.
Given what it lacks and the problems with the content that that it does have, I suggest story tellers wishing to play with archmages would be better off creating the rules out of whole cloth rather than even looking to this for inspiration. To be fair, it is a very affordable game book, but I would prefer to pay substnatially more for a higher quality product.
[1 of 5 Stars!]