We recently took the Hop-On Hop-Off bus tour in Malaysia, and overall, we really enjoyed it. The bus was clean, the staff were polite and attentive, and everything was well organized.
However, at stop number 21 (the one with the horses), we had some inconvenience. We were told we could go inside until 4:00 p.m., but when we arrived, the staff said it was closed and only allowed us to take photos from outside.
Also, there were no benches or shade at this stop, so we had to stand in the heat for about half an hour until the next bus came. It would be nice if the organizers added at least some seating or an umbrella for tourists.