Good way to see main sights, without too much walking. We booked with avios, so no cost. Got on at Unter den Linden. A young lady showed us where to get on. Driver gave us earpieces. We followed commentary in English. Voices were at different volumes, so it meant altering the volume. No bus stops, so had to remember where to get on. It would help if there was a display showing next stop. Bus does not stop long, so if upstairs, you have to descend stairs whilst bus is moving. Only one bell upstairs. We did whole route, stopping twice.