We had a 12 hour layover in Beijing on our way back from Bangkok and I wanted to find something to do while we waited for our flight. I searched for layover tours after seeing a recommendation on Reddit and paid for a great wall tour after reading some great reviews. I messaged Willy the day before while in Bangkok and he responded immediately. We paid via PayPal and had a confirmation shortly after.
Willy picked us up at 6AM on the dot and gave us the option of visiting the main great wall entrance and getting a pass to avoid the line, or heading to another secluded entrance an hour farther. We went with the farther option (partly so we could sleep more on the way) and we got there just in time for sunrise.
The second, more secluded option is the way to go. We hiked up a path to a completely empty stretch of the Great Wall. The sunrise was absolutely spectacular and our guide had an encyclopedic knowledge of Chinese history relating to the construction of the wall and he spoke excellent English. We didn't have any warm clothing since we were returning from Thailand, and he even had winter coats for us to wear!
This was one of the best highlights of my trip to Asia. Willy is great company, a great conversationist, and an even better photographer. He took SO many great pictures of us. We were starving after hiking the wall and he even took us to a small dumpling shop in a village on the way back to the airport. We pigged out and got back to the airport with time to spare.
I'd recommend this tour to anyone I know. It's an excellent deal for the price and you won't be disappointed.