Empires Aflame is an incredible little gem of a product.
BattleTech, due to being a game with a rich history in-game and a long lifespan in real life, has always been a fertile ground for asking "What If?" questions...what if Amaris never launched his coup, what it the Clans invaded earlier or later, what if the FedCom kept going in the War of 3039 and countless others. This questions have been wonderful thought exercises for the fans over the years, even spawning entire Alternate Universe written by dedicated fans. One part of this though, is that the writers and owners of BattleTech have never engaged in this aspect of BattleTech in any official work.
Empires Aflame takes a group of player characters from the mainline BattleTech universe, and thrusts them into a strange setting, utterly alien, and yet, chillingly familiar. The adventure track has good pacing, and gives the players a unique set of choices to let them affect this new setting dramatically.
If I had any complaints about the adventure track, it would only be that the early portions of the track are on fairly tight rails (but with good reason), and that the player characters involved are effectively "trapped" in the new setting, with no possibility of ever going home (again, this is with good reason though, and does fit the logic and technology of BattleTech).
The real meat of this book though, is the "Empires Aflame" setting. Spanning half the book, a GM chapter regarding this alternate universe walks us through what changed it, how it changed, and where the alternate universe is at this point. For any BattleTech fan, it's an interesting read of "what could have been", and presents a compelling universe to game in. For some people, myself included, this incarnation of BattleTech is a ripe new ground for campaigns, and presents a fantastic way to get people involved in BattleTech without having to brief them on thirty years of built up products and information. In short, it's a GM's playground, and has fun with that fact.
In addition to the material in the book for this setting, there is even more material you can get from the module author himself on the official forums. On the forums, search for "Let's Talk About "Empires Aflame" here.", and you can get even more material for this awesome setting.
In short, this is a fun module, a fun read, and a cool new toolbox for GMs. Get this module. You won't be disappointed.