As a PDF - good quality. As with all (most) Malhavoc products, it has a clean, black and white layout making it easy on the printer and quick to scroll through. This one is quite a big product, though.
As a supplement - This is really two books in one. It is part of Malhavoc's 'Event Book' line (also including When the Sky Falls and Requiem for a God) that give guidelines on how to incorporate huge world-changing events into your 'd20 fantasy' game. In this case: War.
So the book includes some of the usual splat-book elements of prestige classes, items and spells, plus some useful notes on what player characters can do during warfare that isn't just endless fighting. These are reasonable, but nothing special.
Then it's also a wargame. Almost two wargames, really - one dealing with small scale skirmishes and another for large scale combat. They're pretty much the same system with a bit of scaling. I don't know how they play out as I haven't used them.
There is a third level of wargame, which covers about three pages, which is a much more abstract system used for fights in the background. It's almost paper-scissors-stone with tactical maneuvres. I've used this when I ran a Dragonlance game (it is very useful for the Battle of the High Clerist's Tower) and it works quite nicely. But perhaps not worth buying the whole book for.