I recently went to Banlung coming from Siem Reap. It is not the most popular way to go to banlung because people usually come from PP, but there is a daily bus coming from Siem Reap anyway. I had my tickets in the hostel I was in Siem Reap (Siem Reap Rooms) from Phnom Penh Sorya Transport. We left very early, at 6am and arrived there at 6pm. Two thirds of the trip was in a paved road, which was quite comfy and there was good aircon too. There was no bathroom at the bus, but there were several stops during the way. The problem was the last one third, that was in a dusty road, but I mean a REALLY dusty road! What made it a nightmare was the fact that a company's crazy guy decided to open the roof window during all the dusty way! Oh my god, I was in the bottom and i had dust all over my body and had breathing problems! When I decided to close the window (because everybody sat there was pissed off about it), the company guy went all the way and opened it again in a very rude way! Awful! But, actually, it was really worth to go to banlung because it is realy beautiful to see such wonderful nature!