On our trip to Cancun November 2013 we took a ferry to isla mujeres. Beware of purse/backpack thiefs. If you are driving a slow golf cart and decide to take a trip around this island, beware of motorcycles. They come up from behind and snatch you bag and there is no way to catch them because golf carts to do not go fast! My tote was tied to the cup holder and they surprised me on my right and grabbed my bag, it happened so fast.
Hurrican Wilma slammed into Cancun in October 2005 and while they are rebuilding quickly you can still see some damage all over the region. Hardest hit was Cancun and Cozumel, Isla Mujeres seemed to weather it pretty well although there was plenty of damaged vegetation you could see along the beach and on the boat as we were going from the downtown area to further along the shore.
I spotted the construction spot in the 1st photo on the 2nd beach where we stopped and I had to laugh at the irony, it doesn't look like a "Playa Paraiso" (beach paradise) to me!
Word around town is a lot of the beach around the island has been eroded from the last hurricane, but not knowing any better, we had no complaints.
Check your vehicle out for scratches & dings and point it out to them. Better still photo them.
You will pay dearly if you scratch it. Credit card is required to rent. Many speed bumps and big.