Try to avoid it if possible, I have used hop on hop off in more than 10 countries, Lyon France’s hop on hop off is the worst.
Staffs was not knowledgeable at all, not wear uniform, you do not know who is staff. You finally asked and know who is staff, he even does not know a location of paid wc just 20 meters away. They just chatting, resting. Do not help customers to answer customer ‘s questions until boarding time, finally start boarding, they started answer questions, kept all other customers waiting outside 30 minutes to be on board. And it was very hot - 32c degree. All waiting outside, inside AC is out of order. They took 2 hours lunch break, how many hours do we have a day as a visitor? They are just too lazy. It is mid September, you call it low season? So it does not worth it at all, do not waste your money and time on it. Make other arrangement.