Nice clear layout, manageable size, good illustrations and descriptions. A bit fiddly having to leaf to the back of the book for the maps, which is a shame, as the maps are very useful for eliminating mis-identified plants due to location.
I like the idea of the keys and got quite excited about them but found using them in anger a bit frustrating. There are a few inconsistencies too, e.g: Arrhenatherum elatius (False Oat-grass) is described as "ligules blunt", but the key for it is DL - Ligule POINTED). I've pretty much given up on the keys now and just leaf through until I spot likely matches then read the descriptions.
All in all a practical field-guide but I'm still not sure about those keys.