Cambodia is best described as having a bad string of luck except their luck has been at work for almost a half-millennium. The country is still poor with many of its citizens living on less than $1US a day and even simple amenities can seem spotty in most areas. But Cambodia has been working hard to increase its popularity among the tourist industry and it's really starting to show. Siem Reap is one of the fastest growing cities and now even sports luxury hotels, an airport, great nightlife, and other attractive things.
Cambodia's economy has only recently become stable and depends heavily on two sources. Those sources are textiles and tourism. While the language of the country is known as Khmer, most of the young speakers prefer to learn English, making it fairly easy to communicate in large urban areas. When you are shopping in Cambodia, it's important to understand that Cambodians aren't the hagglers like their Vietnamese neighbors are. Be respectful since most aren't going to high ball the price to get you to haggle over it unless you are in a major tourist hub. Also, your US dollars will be pretty universally accepted so it's not absolutely necessary to exchange your currency unless you want to.
One of the popular things to do in Cambodia is to travel Tonle Sap. This is the large lake that you often see in the middle of the map and is a main way of transportation around the country. It can be a long boat ride depending on where you're going but the views of the shore and you'll get to see local life around the shoreline. Other popular destinations include the city of Kompon Luong, a popular town that is completely afloat in the Tonle Sap.
There are many ancient ruins and beaches that tourists the world over have had the opportunity to enjoy. Spread across Cambodia's geography are great national parks like the Bokor National Park and Angkor Archeological Park. Another popular temple is the Preah Vihear which actually pre-dates Angkor. If you enjoy birds, consider paying a visit to Prek Toal Biosphere Reserve which is considered to be Southeast Asia's premiere bird sanctuary. Cambodia has a lot to offer the thrifty traveler who wants to see Southeast Asia but doesn't want to spend a fortune doing it. The ruins and beaches are second to none and the major cities continue to accommodate tourists. I have visited Angkor four times and will be going back again I hope this give you an idea how interesting the place is.