I've eaten at many Chinese places around the Champaign-Urbana area and this is by far the best one I have tried.
Rainbow Garden is great for dining in or taking out. The service is excellent and the food is always fantastic. I've tried a few different things from the menu and have thoroughly enjoyed each of them.
The prices are about the same as any other Chinese restaurant in the area as are the portions (unless you have a large appetite, one dish can usually provide two meals). My only complaint is that while dining in they do not provide enough rice with their meals. This isn't a problem, though, as they are happy to give you more upon request.