I feel that I'm in a unique position to give this guide a proper review since I'll be moving to Ireland in less than 2 months from now. So consider this a preliminary review and I'll follow it up once I really put it to use across the pond.
My immediate impression was it's size. If you are familiar with David Crossley's previous 2 ID guides, Eastern (US) Birds and Raptors you will know that they are large tomes. Both are 7.5x10 inches,with Eastern Birds being much thicker. But the Britain & Ireland guide is smaller, only 6x9 inches. But feels much more compact and portable. This is still not a book to be casually placed in a pocket when heading out into the field, but it would more easily fit into a bag. From what I can tell, the descriptions of the individual birds are not located at the bottom of each page, there's no wall of text in the back of this guide like the Raptor guide, the only other one that I own (I've been waiting for the Western version of NA to be released since I first saw test plates of the first book). Unfortunately too, my copy of the Crossley ID Guide: Raptors is one of the many books that are currently sitting in a warehouse in New Mexico somewhere.
I really like it, I even had a chance to use it too. There was a Tufted Duck in Portland last month and I went down to try and see it. Unfortunately I only saw a thousand or so Greater and Lesser Scaup. But I knew the proper field mark, dark back, because I had the ID Guide with me. I really can't wait to use it in Ireland, which is less than 2 months from now. I plan on writing a follow-up post about how well I pick up on their birds. I already know that their short-hand codes don't make sense to me. And I'll learn to call Chickadees Tits and Loons Divers to fit in.
So far I can't recommend the guide enough for anyone hoping to go to the UK and/or Ireland from the US. I agree with another review that I read which said that the North American names of birds found in both hemispheres should have been included, and I plan on doing that myself with post-it notes at some point. But I guess that I'll just have to get used to Loons being called Divers, Chickadees becoming tits and not looking at Starlings and House Sparrows with scorn.
I had also taken some photos of the book, but my camera and lenses were recently stolen, which I'll come back to.