The Hop On Hop Off Tour in Berlin is NOT good. The Bus just takes you in one direction. It does not ply in reverse so if missed out something then you have to take another round that two hours again. The price does not justify the tour. There are many much cheaper and better options available. However TV Tower is worth watching. But Viator is good.
The trip was very gud and the lady guide new it all quite well and the way she explained was just fantastic.