First, the walk. It follows, roughly, Robert Louis Stevenson's 1878 journey, which he turned into "Travels with a Donkey in the Ceevennes", his first best seller. The walk is mostly in the Cevennes, one of France's least populated areas, relatively unknown to British tourists, and very beauutiful. The trail, France's GR (Grande Route@) 70 is largely in hills and mountains, up to 1695 metres, in remote country, often looking like Scotland, including gorse and heather. The walk includes medieval sheep trails, disused railway line (including tunnels) and mountain paths and passes.
Second, the book. First, the directions are clear and extremely helpful. Along with excellent French waymarks, it makes clear which paths to take (and not take). I never got lost, and am no orienteer. Second, the proposed days walks are well judged, with longer and shorter options and variations. The longest day was 17 miles, with about 700 metres of up and 1000 of down (most, but not all, gradual). So hard work, but not enough to take the pleasure away. Third, it includes some useful practical information and guide to places.
Third, some tips. First, maps. This book recommends the French IGN 1:25,000 maps. I bought from Stamfords the IGN (so in French) 'Chemin Stevenson' Topoguide, which included both 1:50,000 route maps and background on the region, and that was enough for me. Second, the Cevennes can be cold and wet - in late April, I had rain and sleet and (unseasonal) snow. Third, visit [...] for lots of practical information, including accommodation. Finally, buy the RLS book, and enjoy the walk.