I enjoyed my stay in the Red Bus.
It was well designed and felt very spacious.
The loo is in a separate building ( very close by) and hard to see in the dark until you've made it to the other side of the bus so I recommend bringing a torch if you don't have great night vision.
The bus is on the hosts property and has its own area- I could see and hear people coming and going so it wasn't quite as quiet or private as I anticipated.
I still think it was worth the experience though.
I would definitely recommend staying in the Red Bus at least once.