What can I say. One of the best miniature rulesets to come out in the last couple of years. While it is nominally presented at 15mm skirmish scale, the rules work equally well with 6mm, 10mm, 20mm and 28mm scales. Even larger if you prefer. Just adjust ranges accordingly. Personally I've played Gruntz with 15mm and 28mm/30mm scales and only range conversion needed was moving from centimeters to inches. The game plays reasonably fast but still feels that your force's tactical flexibility is not limited. There's also quite extensive alternative rules section to customize the game your personal preference and miniature collection.
One of the biggest draws of Gruntz is that it has point buy unit builder. All the sample armylists are build with the same structure and can be customized to your liking. Ever had a cool idea for a character, a vehicle or a unit but the fixed armylists don't really reflect your idea. With Gruntz you can do this. Downside of this is that unless you have a really clear idea what you want from your army units, the unit building can be a bit much for new players. Luckily the book gives good examples.
All in all, highly recommended for experienced miniature gamers.
[4 of 5 Stars!]