I have read and enjoyed all of Colin Fletcher's books. I found him to be a superb writer, by the test that he could write about nearly anything and have something interesting to say. He was not an adventurer, and his books were not about adventures - they were (with the obvious exception of The Complete Walker)essentially short autobiographies, covering the period of time spent on that particular trip. Certainly not something that would be to everyone's taste. Fletcher was a writer who took to walking (his first book, The Thousand Mile Summer, was about a trip taken specifically for the purpose of writing a series of newspaper articles), rather than a walker who took to writing.
To enjoy his writing to the maximum, it helps to be a little bit like him, I suppose - both introspective and prone to careful observation of the world around you.
Exciting, his books are not. But they do give you what they intend to give you - a very good idea of what it was like for him as he pursued each trip.
By the way, If you want a quite different experience of Fletcher's writing skills, I would suggest The Man From The Cave.