Thai Smile was great domestically. Have flown Thai Airways many times previously roundtrip between BKK-NRT (Japan). Nothing at all special about Thai. Staff were just OK. Finished cabin service, then hid in the galleys eating and talking until the landing service, every single time. Tiny, thimble sized cups and glasses. Had to get up and hunt them down in the galley for another drink or coffee. Delta is far better internationally and back in the day, Northwest Airlines (NWA) was superior too. Flying Qatar in September to Africa and surely they will far exceed anything Thai provides, in all aspects.
Disclaimer: have not flown Thai in 5 years, so perhaps they have improved. Hope so.