Okay, so not sure if you're familiar with me; I'm a pretty prolific reviewer and I have reviewed the original ethermancer (+supplemental material). One of my players loved it and wrote an optimization guide, which has become a kind of design guideline for the new book. Also, Bradley, the author of the original pieces, got me and Jason Linker on board and the result is...well. Awesome.
The book is over 90 pages long, and sports two new base classes, the ethermagus (all about making deadly etherblades) and my own etherslinger - which is what the gunslinger should have been: Highly modular 3/4 BAB-class of gunslinging + ether magic, with tight, versatile resource-management. Kick ass even when you miss, wrap yourself in alterations as you put bullets into your enemy, be actually capable of stealth missions and underwater adventures, shoot down haunts, make impromptu minefields, generate bullets (and even guns!) from thin air, optionally add ki for WuXia-campaigns - and that's all BEFORE the expanded ethermagic. Granted, I might be biased towards the class, but everyone I've talked to about it loves it.
Remember those options that didn't really work so well for the ethermancer? Well, the new classes get quite a bit out of them.
If you have any questions, drop me a line via the contact tab of endzeitgeist.com; Next week, the review of UE will hit that site as well.