Decent - seats were ok, bus took an couple more hours than was expected (especially as the bus I got back to Phnom Penh was 4 hours), stops for toilet and food at a restaurant. Restaurant comes quite lowly rated on google maps and is expensive for Cambodian standards. Recommend to bring own snacks and food and just be aware of travel time being longer.
Airbus, Angkor Guide Adventure, Chan Moly Roth Transportation, Dara Panha Sak Transport, Go Ho Travel, Koh Rong Island Transport, Olongpich Transport, Sensok San Bus, Sovan Rithy Express, Virak Buntham Express