The Mae Sot-Mae Ramad section (approx. 35km) is still partially under construction. There will eventually be 4 lanes all the way between the two districts, so far the sections from Mae Sot to the 2nd Friendship Road intersection, as well as the road all the way to the new bridge are now complete, but there are still some sections under construction after that. However, due to the rainy season major construction works have slowed down until the dry season begins.
North of Mae Ramad to Mae Sariang is in pretty good condition most of the way; there may be a couple of small landslides and a few potholes here and there just before Mae Sariang (the road between Mae Ramad and Mae Sariang is quite winding in places, but not excessively so). No idea about Mae Sariang to Mae Hong Son as I've never been up that way, but from what I've read and heard, it seems to be quite good but winding.
Indeed the Mae Sot-Tak road is a mess, well starting from just after the Doi Musoe market to the Pawo temple at least (approx. 36km). The first section from Tak to Doi Musoe is complete and in excellent condition, but you'll regret going this way as soon as you're at the bottom of the Musoe mountain. An alternative is route 1175 from Ban Tak to Mae Ramad. Excellent road, a little winding before Mae Ramad but hardly any traffic. Only nuisance are the checkpoints, which are more thorough than the ones on the Tak-Mae Sot road.
