I rode this at the beginning of December (2006), and there were still 2 patches of unmade road, one around 100m long in some hills about 50km south of Mae Sariang, the other about 4-500m long about 50k further south. The rest is fairly typical of the region - some rough, repaired surfaces, and in other places fairly newly laid. Not many petrol stations, as I recall, so remember to fill up in Mae Sariang.