Love that book! I'm gathering and reading all the Iron warriors novels at the moment. Me and the Mrs are travelling by train through France so I should be able to get a few under my belt on the TGV!
I agree that the balance between the forces is great, and the writing gives a really good insight into each chapters methodology to waging war. Some parts are downright horrific, and you lurch between rooting for the iron warriors and hating their very existence - which i guess sums up their very essence!
BL did a new omnibus which gathers all the Ultra/IW books into one and in order so its possibly worth reading just to flesh out the whole story!