Recently took a tour with David and it was a great experience! I had arrived late the previous evening and David had no problem picking me up at my hotel a little later in the morning. David was the perfect tour guide in that he knows his stuff and will answer any questions you have but at the same time, doesn't smother you with information, which allows you to take in the ruins at your own pace. Also, being out all afternoon in the Cambodian heat can be a bit oppressive but since David had an air conditioned car, it made a huge difference in being able to enjoy the experience more overall. Coming from a person who rarely takes guided tours, this was worth every penny and I can't recommend it more.