In Cambodia nearly everything (for foreigners at least) is paid for in US dollars, the local currency (Riel) is for the cents; we made sure we got some low-denomination dollars when we changed our Bahts at the airport as we knew change could be a problem.
Cambodia looks a lot poorer than Thailand. Phnom Penh is very low-rise, dusty and more unkept than Bangkok. We saw some slum areas and a few beggars (in nearly a month in Thailand we only saw one beggar) on our way to the hotel. Also the guide book says the medical situation is a bit of a shambles and for anything serious you need evacuation. We have a good insurance and are well stocked up on medicines. Our hotel is in the backpacker part of town, and on the street here things are better, though not quite luxurious. The hotel is great: modern, clean and with a small indoor swimming pool (more like a cold Roman bath). And yes, Lucas fell on his knee again.
Lesson learnt today: I shall not sneer at farangs for eating western food; our first meal in Cambodia was at a pizzeria.