This is a superb walk with a wonderful guidebook by the late A.W.Wainwright - printed in his own handwriting with pen and ink maps and sketches. I've walked many of the individual bits of the walk, but never done it all in one go - I probably never will, now (too busy playing the banjo!). There's an account of someone else's completion of the walk here, with lots of useful information.
Cheers
Ray