I concur that it is a good book that has obviously had a lot of effort dispensed in its production. Aside from Syl's previous trilogy on the subject, there are a couple other books on the subject, for those that are interested, that also offer a great deal of useful information.
Fly Fishing: A North Country Tradition by Leslie Magee
A Handbook of North Country Trout Flies by Roger Fogg
As it is, Syl's new book doesn't address these titles in great detail, if at all, which I found unfortunate as they are probably the most informative and concise I have ever read on the subject matter. John Jackson's work "The Practical Fly Fisher" and Skues' "Silk Feather and Fur" were also titles I would have thought to have seen mentioned as well as Syl's own work "Soft-Hackled Fly Imitations". The latter is important, in my opinion, because it relates the patterns of yore to American hatches with more specificity than Leisenring's work (which is also very good by the way).
I have found that www.abebooks.com
is a great source for locating these older titles.
While on the subject of soft-hackled spiders, Alec ackson has recently introduced his NEW Soft Hackle Hook. It is a 2x short, 1x fine, straight-eye, Limerick bend hook with the trademarked Daiichi "Crystal Finish". These are very nice hooks that make a very sexy chassis for some elegant softies in the spirit of those tied by Walbran, Brumfitt, Pritt, et al.
I'll try to post a pic of the hooks if I can find one.