I had the pleasure of staying at the yak in Playa del Carmen and I have had a great time.
The staff really invests its time in making the guests have a good time - almost every night there is some kind of activity - a movie, party, dinner. These kind of things really bring people together.
In addition, the hostel has 2 kitchens that are both very clean and fully equipped.
The mattresses are very comfortable, not like the ones you find in cheap hostels.
Overall, highly recommended , especially if you travel solo