My trip from Ho Chi Minh City to Gia Lai was with TT bus company, but I wasn't satisfied, so I tried Duc Dat bus company. The driver, conductor, and call center staff were all very friendly. In Gia Lai, someone called ahead to give the driver's number, then I went to the bus station to wait for the bus, unlike the Ho Chi Minh City trip where you have to change tickets. Before boarding, the driver asked for my name and the phone number I used to book the ticket. The bus was slightly late (because some passengers arrived late, so they had to wait for them, but the bus arrived on time). But it ran incredibly smoothly, without sudden braking like with TT buses. The downside: the buses are older than TT buses, the interior isn't as luxurious, but they both have USB A ports for charging. The upside: polite service, no smoking on the bus, individual mini pillows, and a smooth ride.