I took a long time to choose a wild flower guide. I wanted one about Western Europe, as I live in Portugal. I choose this book as it seemed the only one suitable for my needs. I don't regret it, but I need a more complete one already. Specially about plants close to the dunes and sea flora in Portuguese coast, there is still more to do related to this book.
At first, the identification key was very hard to understand, as I was used to other kind (Fitter, Richard). But now i understand it and I like it - I must say though that i am just a beginner and a amateur and i had never studied plants in my life. But together with a not-so-good Portuguese guide (with photos only)- Conhecer as plantas no seu habitat by Pinho, Rosa et al. -, I have been managing to identify lots of new wild flowers.
So i recommend this book for the starter, but maybe it's not enough after some time, if you are really interested, of course!