There are just a couple of restaurants in town, but if you are on a budget trip you'll find nice very reasonable food just on the markets west front. There are some cookeries with quite a wide range of cheap Khmer, Chinese and Lao food open until the early night. Late afternoon the typical small stalls offering several fruit juices and delicious baguettes.
This nice decorated caf and restaurant halfway from the centre to the airport is not only a place to eat but to see beautiful silk weaving settled in a gallery style. They offer light Cambodian but also some Western food.
They make the most of their parkway location by having a small sidewalk eating area. It's a pleasant enough early evening spot as the locals ride by on their evening motorcycle pleasure cruise. They have good food (Western and Khmer), and an English menu to go along with English-speaking staff.
This restaurant is just one block west from the market and offers a mix of Asian flavours from Cambodia, Thailand and China plus a fair selection of beers.
Located across the parkway from the Arunreas, this place is easy to spot, as it always seems to have Coca Cola and Player umbrellas set up. The food is tasty, but is prepared to try your hand at Khmer as they don't speak English and there isn't an English menu. The staffs are very friendly, though.
Good Khmer and Chinese food with an English menu and beer girls, to boot.