The staff were lovely and the bus was timely and snacks and drinks were provided which were fine. The seats weren't the most comfortable. We would recommend getting their first class option.
The toilet was clean enough and an overall decent journey for a long bus ride!
You sell the ticket from don Meuang, the 2nd station in the line Ban sue-Ubon. Ban sue is closer to Bangkok center and much easier to reach. Don Meuang is 18km away. I would like to know WHY?