Stayed here with family and it was great. As for the building it is topnotch clean, well appointed and functional. We stayed in the bottom unit on the street side. This unit was large and had plenty of space for us and more room for the beach stuff outside our room. Having a (secure) parking spot is great if you rent a car. The building itself is secure and the other guests were great plus there was room for everyone in the courtyard and outdoor kitchen. The kids spent a lot of time in the pool and playing ball in the covered parking area...also good for hammocks!
The furnishings were solid, clean and tasteful. From just looking around the town (we were there 10 days) it was one of the nicer places for sure and always a nice place to come home to.
We usually went for a roof top cocktail and from there you could see around quite well and over to the beach strip and ocean. There was a car rental agency close by with a Mexican/Canadian couple so there was some easy to come by local tips.
Getting into Merida was easy even if you walk and use the public transit. The city is a bit cosmopolitan without the size of the larger cities so with young kids it was easy and fun.
If we were to go back to this area we would no doubt come back to Casa Sol Mar.

I stayed at Casa Sol Mar for a couple of weeks over Christmas last year. I found the accommodation to be very well presented, clean and in an excellent location. Moments from the beach, local bars, restaurants and shops. The apartment itself was very comfortable and airy, equipped fully to self cater if you fancy a night in. However this never happened on my trip, as the shared area with swimming pool and bar was a great place to chill out with friends, and meet some other guests that were holidaying in another apartment in the complex. Being Scottish, i didn't think i could have such a good time at Christmas without snow!