This is certainly the best way to see Berlin in a short time. The route took in all of Berlin and the major sights.
Finding where the bus stopped was pretty challenging. There are no bus stop posts or signs and several times we had to run to catch up with the bus in order to get on it! We hadn't realised that the viator ticket was not for both routes (A and B) so had to pay extra in cash to use the B route. There were half hour stops in places the were not particularly conducive to getting off especially in the rain!
The commentary was borderline racist and definitely sexist. That said, we did enjoy our trip around a fabulous city.

The tour operators were fantastic. High frequency and multiple stops throughout the city. Highly recommended.

Joined the bus just outside our hotel, first problem was that they didn’t wan5 to take our aviator voucher, eventually we were advised that we could go to a different bus where the tickets could be printed.The driver of this bus didn’t even acknowledge us but he did print the ticket and we boarded the bus, he certainly wasn’t the most customer friendly person I have met, there are many stops on this tour and I would advise that it is slow going around the city due to the heavy traffic, one thing that wasn’t done was the advice of each stop and what the particular sites were available, it’s still probably worth going on this trip if only to give you an overview of the city.

Although I arrived in Berlin in the morning, I didn't head for the HOHO bus immediately. I purposely took the public bus 245 alt-moabit area to Potsdam Platz. From there I board the HOHO bus and enjoyed the entire journey. This activity is recommended as it covers most of the places of interest in the city centre

I really liked to use the buses the drivers are very friendly, as well as the people who attend, they have 2 bus lines the A and B, you identify each stop because there is a person attending in each bus stop and they are wearing red jackets. Ann

Meh. It's a great way to see Berlin but I would have rather done a small group tour.

It's a must tour if you want to see all of Berlin's attractions. 2 tours red and green as well as boat tour make you see all of east and west Berlin

Save your money. This kind of bus tour is useful for some cities, but not Berlin. You're better off doing a Berlin Highlights walking tour and taking a bus/subway to other major sites.

Booked the 48-hour pass plus boat trip on-line before arrival. Easy to find the bus stop location, which was near our Hotel (H2 Alexanderplatz). We did both tours, the classic 1st, including our boat tour (which was great), and the East side tour on the 2nd day, stopping off at Mauer Park for the flea market and Karaoke ! (only on Sundays). Very good tours, great value for money.

I used Hop-on Hop off bus in several cities in the past.
The one in Berlin was the worst. The audio quality was bad, besides most of the time, I could only hear the music.
It was a waste of time and money.