I love everything about this and I have always wanted to make armies more than just a background field of mooks in an encounter, but rather something the players can actively pursue with all their misbegotten gold.
Matt Covell is a great GM, and he's a fantastic spokesman for our hobby. I'm a big fan. The book he produced, Strongholds and Followers, is a class-A top-tier product. The book is of great quality, the art direction is unique and wonderful, and Matt's familiar writing style makes you feel as if he's sitting in the room with you explaining the rules over a beer. Everything about it screams quality in production.
The rules and ideas he presents are original and seem to be fun. A lot of work and imagination went into this product. The tables are thorough and well thought out, and you grok what the system is trying to do in very short order.
If I had a knock on the product it would be that you need to run a campaign that will accommodate the rules. Matt says up front that using the book will require a lot more work from the GM, and I think he's right. It's a ton more work. And the players have to have complete buy in that they are building a stronghold. If you run a travelling group of adventurers, this book won't work. If the PCs want to settle down and build a home, this is the only book you need.
Strongholds & Followers is a carefully thought out, well-articulated, intricate piece of work designed to reward your players while providing more interesting hooks and narrative to your game. The concept of class-based strongholds that provide specific and potentially wide-ranging benefits could really push the right kind of game forward. The quality of production and artwork in the book is fantastic and I want to use it just to show off how nice the book is.
On the other hand, there is something very... 3E about this book. It almost feels too crunchy. Perhaps too powerful (RNG gods be praised or damned depending). Too rigid. I know this fits Matt's (the author) vision and style very well. I think many DM's would get along great with this book, but I do think that it is somewhat harder to adapt verbatim than other forays into similar components for D&D-style games. There is a ton of terrific and detailed support in this book, but at the same time it has a very distinct flavor. Many DM's may find it takes as much work to adapt the book content as to lift the mechanisms right out and redo everything to their liking.
I think, to a large extent, this will be true of any book as ambitious as this one. It is a great read and sure to spark ideas for any game. If you are looking to make your game richer, more immersive, and deeper you could do a lot worse than to give Strongholds & Followers a look.