We took the tour in November 2002. Loved it! It was an air conditioned bus. It's a very efficient way to learn a lot about the two sides in a short time. They make many stops at various sites for you to get out and take pictures and tour.
Be aware that at every site, your bus driver/guide is not allowed to be your guide at the site. They have guides manning each site and they "expect" a tip after each tour. We gave each one $1 to $2. I think there were five all together.
The marketplace that they stop at on the French side was wonderful with great deals and prices -- but we felt they didn't give us nearly enough time to shop. There was a 1786 fort there -- Fort Louis -- that my husband (the history buff that he is) wanted to see -- so he ran to the top of the very big hill/cliff and saw it and took pictures and ran down and was back in 30 minutes! But he said it was really worth it.
We always take the island tours (St. John, Nassau, St. Maarten). We feel you can learn much more that way for a more economical price then trying to get taxis or rent a car. Plus, so far, all of the guides we have had were very colorful, knowledgeable and really rich in the local history.