Don't pass up on it, as it is a good read and provides some great detail. The whiners fall into the usual category of a small minority who wish for The Reunification War - Volumes I-XXV each of which would be a 500 page monster in and of itself and totaly focused on thier Fanboy and faction specific dreams.
Catalyst have done a good job of taking old and conflicting material, which was coloured a nice shade or rose, of a massive 20 year conflict and condensed it into a managable book, which provides an enormous amount of new and detailed canon material, as well as a good look at this mamoth conflict.
Are there errors and a few odd bits that crept in? Yes there are.
Will it piss the fanboys off? Yes it will.
Is it revisionist? As with all history, of course it is.
Does it provide a great look at the reunification war and the state of every realm at the time. YES IT DOES.
And for that last point, it is one of the most valuble books Catalyst have produced in recent years.