I have the book and was just a little disappointed by it. There is a small technical appendix dealing with some experimental data - but much more with the mathematical models for distance, weight, speed and penetration etc. which were hinted at in Hardy's eearlier book. The rest of "The Great Warbow" is a history of its tactical use in various battles, which is great if that is what you are interested in. Strickland's main thesis is that the longbow only came into its own once the tactic of using dismounted men at arms and archers together was developed.
If you are intersted in the military history and tactics its good, but there is comparatively little info in it about the bows.