HG Blitz is the basic rule book for Heavy Gear. You will need the Heavy Gear Field Manual to go a long with this if you purchase the book. The book is laid out fairly well with a lot of diagrams and pictures for you to reference. The rules section has been replaced by the field manual. But that is OK most of this book contains the background information on Terra Nova. It also hosts the information you need to build most of the armies you are allowed to play in Heavy Gear. If I didn't purchase this product I would not have found a new miniatures game to play.
HG has some unique approaches to their game mechanics. The first is Margin of Success (MoS). Basically players roll a number of dice equal to their skill level and take the highest die roll. Then they compare the roll and subtract to get the difference. The difference determines failure or success. I think it is one of the best dice mechanics out there.
The second, is it is an action point system. That is each model or combined model has x actions. Actions can be used at any time during your movement. It requires one action to move at top speed.
The third, is it is a game of combined arms. Your choices vary from list to list but you get to choose from infantry, gears, and tanks.
The final unique item is command points. Command points add a whole new element to the game that I am yet to experience.
What I really like about Heavy Gear is that the game is truly about the tactics you employ. You do need to have a good understanding of what is in play and what the terrain allows for, but the good news about that is it is the same for everyone.
We have a lot of videos on Heavy gear over at gamer-goggles.com feel free to check them out.