Stayed there last August. For those interested in the differences between the Pueblo Bonito Mazatlan and Emerald Bay, my humble opinion:
The Emerald bay positives:
Lovely gardens and more luxurious sorroundings.
Great food in restaurants.
Emerald bay negatives:
Far away from Mazatlan town ( a positive for some)
The beach is dangerous.
Check in service very slow...
Pueblo Bonito Mazatlan positives:
Great beach, and restaurant overlooking the beach...
Great restaurants and services.
Pueblo bonito negatives:
The hotel is not as nice and luxurious as Emerald bay.
The good news is that there is a shuttle bus from and to both hotels. So, if you have an all inclusive option, you can have a great time in both hotels.