Noisy!
Stayed for a week a couple of years ago. Much of my visit was unpleasant, due to significant lack of sleep.
When next door neighbors came home (often at 2:00 in the morning), they may as well have been inside OUR room. I had to get up, open our door and ask them to move INside their room. Even after that, we continued to hear their conversations, etc. from their adjacent rooms. You can hear every door open, every flush of the neighbor's toilet, etc.
We could also hear (couldn't get away from the noise of) other (non-adjacent) guests, since the windows, door and walls offer virtually no sound insulation. Lastly, the noise of the beach-side disco, about a half-mile to the south, pounded into our room until ~4:00 in the morning. Touching the inside of our window, you could FEEL the vibration from the disco. I could actually understand what the DJ at that disco was calling out to their patrons, it was so loud!
When we inquired about rooms with a different orientation, we were told that the only ones available were on the ground floor, facing the same courtyard our upper unit faced. We were advised that changing to one of those rooms was not recommended . . . because the noise from upstairs guests was known to be disturbing to those below!
My recollection of my week in Mazatlan is vague and unpleasant - and that all resulted from being progressively less rested as each day passed.
I would not recommend the hotel.