I ordered this as a modern version of the Hamlyn's and Collin's field study guides I have used for many years. My daughter wanted her own guide and we considered this alongside the RSPB Pocket Guide to British Birds
. The introduction says this is NOT principally intended as a field guide, yet when looking to choose one, this was the nearest I could find to my 'old faithfuls'.
So far as I have been able to determine (and I'm just an enthusiast not an expert) this is an acceptable update. It covers all the identification factors I would look for - appearance in flight, at different times of year, at different stages of development, description of calls, distribution areas, etc.
There is a section on bird topography (how to describe the 'parts' of a bird's physique and plumage) and also a section that links local, common, scientific and international names, so if you need a description of a Brook Ousel (Water Rail) or a Yarwelp (Avocet), they are there to be found.
The immediate difference is the colour photos rather than drawings of each species. Also it limits itself to 280 species that regularly occur in Britain and Ireland as residents or visitors so if you were lucky enough to spot an 'accidental' from Europe, you might not establish an identity. Then again, if you are good enough to know it is an accidental, you will have other guides available!
There isn't a species comparison page (for the various birds of prey for example) and I miss that - you would have to look at the entry for each possibility whereas my well-loved old guides had a comparison page that showed the outline given by all comparable species for quick identification, then turn to the detailed entry for more information.
Ultimately, my daughter chose the pocket edition, specifically because of its size, but I liked this enough to keep it for the car.