A chance to see one of the modern wonders of the world. Worth the trip if you study and know what you are looking at. If you are only interested in cool ruins, there are closer ones such as Uxmal that may do the trick for you if you want to avoid a two hour bus ride. For this tour, use the cruiseline. May be $45 more per person, but you won't be left behind.
Went by taxi at recommendation of taxi personnel. Not free. Highly developed beach at a bar, charged for use of facilities. Bottom is rocky. We didn't have enough cash once we arrived due to taxi fare and no prior knowledge. Will book a snorkeling excursion next time.