Just back from Thailand, Malaysia and Singapore. Pretty much flawless service from Uber in Bangkok, Chiang Mai, Penang, and Ipoh and Singapore. And cheap too, barely any of my journeys in Penang or Chiang Mai were more than $1!
Chiang Mai is very new, had only been up and running a week or so, so drivers were still getting used to Uber. In fact one driver must have messed up because I only got charged for the final 200 yards of the journey (I tried to contact Uber to make sure he's paid for the remainder, but they don't seem to want to help.) Another driver turned up in a pickup with her brother in the passenger seat and son lying down in the back of the pickup - I didn't have the heart to complain.
Bangkok was the hardest place to use. From the airport was fine, and the driver easily found me on the correct door of arrivals. Other rides were more difficult. They all seemed to ignore where I had placed the pin, phone me to ask were I was (sometimes in English) and then ignore that too. Coupled with the fact that if you spend more than 15 seconds by the side of the road looking out for your ride, you'll have 400 taxi drivers trying to pick you up...
Was in Phuket and Koh Samui too, where Uber don't operate. Very much missed them there.