I bought a copy a couple of days ago and I haven't had time yet to look at it in detail, but on a general overview my reaction is very positive. The format is complete games rather than variation trees, which I think suits the material well; the annotations are detailed, and provide a good balance of analysis of moves and verbal explanations. There are also some Q&A's and exercises. In the Stonewall it is particularly important to understand how different plans and piece configurations suit different pawn structures, and how the pawn structure can be transformed in different circumstances, and the authors definitely pay attention to these factors. Co-author Bern and contributor Agdestein annotate thier own games informatively.

In addition to the main lines, there is coverage of all the anti-Dutch lines I could think of. Personally I don't play 1...f5 in response to 1.Nf3 or 1.c4 (I think a Leningrad move order is OK after 1.c4, but I don't do badly with 1...e5 so I'm sticking with it), and after a brief read of the chapter on these moves I haven't changed my mind. However the lines given do look playable, particularly if you are happy with the black side of 1.Nf3 f5 2. d3 Nc6 3. e4 e5 (this is the opinion of a 2100 player, and I hope one of the stronger players on the forum chips in with some views).

In conclusion, it looks like everything I was hoping for and I recommend it without hesitation.