We cruised on the RV Samatha in Nov 17 from Yangon to Mandalay.
The cruise was a delight or at least the onboard component. Burma itself is third-world and poor but the people seem friendly - “seem” because you don’t have much interaction with them.
The food on the boat is superb, the best we’ve tasted on a cruise. I heard no complaints and the APT company seem to have a reputation for good food and service.