Cancún is a hateful place
Born of the
Mexican government strategy of highly developing pristine spots in the
coastline, filling them up with hotels and then selling them to foreign capital groups (the
money goes out of the country: the
pollution stays in), Cancún is an exercise in
concrete gone wild.
Basically the place did not exist until it was developed. There is no old city centre. All is modern, in the bad sense of modern.
The worst bit is no doubt the main beach, completely raped by enormous buildings and accessible only by a road that (get this) has no sidewalk !
Basically, the best part of the place has been sold and shat upon.
Use Cancún only as a cheap air access to Yucatan. Once you land, get the hell out of town. And the climate is terrible: hot and mega-humid. Great if you fancy heatstroke and sunburn.
This having been said, the city market is not bad, and the seafood is tasty.
Anyway, if you want a place that is more real, less corporate and has access to sea, I would take Veracruz or Villahermosa, Tabasco any day.