We have stayed there for 4 nights around New Year. After over 3 month of wooden bungalows, shared bathrooms and cold water it was paradise for us.
The linen is perfectly fresh and clean, the bed comfortable. If you get a room with the riverview, you will pay around 120000LAK, if not - around 100000LAK. It is a little noisy (like everywhere on this street), but the riverview room - less (we have tryied both). Try to get on the third floor, it's quieter.
The staff is not particularly welcoming, but we didn't really care, as they were polite.
It is a little expensive, - we have seen some good gueshouses in the same street for around 80 000 LAK, but those were all full.
We'd recommend the Domon, you get what you pay, it's comfy and clean.