We stayed in Miquela's Costitx' townhouse and everything was great.
Very easy checkin, the host was always reachable. The house was fully stocked and ready for us (maybe bring some soap :)).
We spent a week in September 2017 cycling across Mallorca, the central location of Costitx made for a great starting point for all kinds of tours. If you go by car (which you will need) it's even easier and faster to reach everywhere. Lots of food options 10-15 minutes drive away (in Sineu for instance). The town itself is cute with a bakery and a couple of bars.
The roof hottub was highly popular after cycling trips :).
Miquela was great, providing us with fruits, home-made goods and even some wine on checkin and was always reachable.
I recommend staying in her airbnb and we'll be back next cycling season