It's a great way to get around. At first I was nervous about how to 'do it', but there's no need to be. The drivers were friendly, helpful and more than happy to take the fare in tourist currency: the CUC. You'll pay more than the locals that way but it'll be considerably cheaper than the yellow 'tourist' taxis. Cheapness is not the reason to do it though. It's a fun and enjoyable way to travel the city.
Everyone seemed content to watch the world of the street passing by the windows and enjoy the breeze coming in. There was something very companionable about sharing the ride, strangers travelling the same way for a few minutes before carrying on with our individual journeys.