I am almost done reading the travails of Tamurkhan, the nurgle commander who decides to fight his way through pretty much the entire Warhammer world, so he can have a shot at the Empire. I'll tell you, it is thoroughly enjoyable, (although better suited to readers over 12) and a perfect lunch-at-work-read.
I am always inspired by imagery conjured up by warhammer/40k writers and this one totally got me going. Boy, I would love to build a Night Goblin Army now, the way they (almost) kicked ass.....thoughts are slowly building here. I don't want to spoil too much, but those Gobbos are awesome. There are many more races featured and we learn some new stuff about all of them, although the main part is about power struggles and religious fractions with Chaos.
I know it's expensive, but it is certainly worth it. The artwork is astounding, there are NO models in it (great) and the main story is almost 100 pages long. The 2nd 100 pages deals with armylists and other stats.
Anyway, just giving my two cents here, before you buy more spacemarine tanks that you kind of don't need..get this one. You will be stoked!