Our stay at Balcon de Cala Santanyi was exceptional. We have four kids (5 - 16) and the location was superb for the beach, swimming, snorkling, climbing and walking. The water is extremely clean and clear and brimming with fish.
The local restaurants were amazing; excellent food and very good value. We ate out a lot, but when we cooked at the house, we found the kitchen to be extremely well stocked. The house is a little old fashioned, but that really is part of the charm, and we wanted for nothing during our stay.
We arrived in the middle of the night as our flight was delayed and our hosts had left milkshake, juice, milk, coffee and fruit for us. This was really appreciated as we had four hungry children in the morning and at that stage we didn't realise that there was a spar only a few metres away.
We would note a few things though which might improve other peoples' stays;
Cala Santanyi is not well serviced by bus. We were unable to rent a car as our flight arrived in the small hours of the morning and all the car hire companies were closed. If you really want to get about, you should make sure you rent a car as the connections with the bus are irregular and tight. We actually found that not having a car was a bonus, we didn't explore the whole of Mallorca, but we did relax a lot in Cala Santanyi and the neighbouring coves.
The local shop doesn't stock much in the way of meat/fish for dinner. You'll need a car to get to a decent supermarket, although if you don't have a car (like us!) there is a larger shop in Cala Figuera.
It appears that the local shop might close for the winter months (there was a sign saying that it was closing in November).
The mosquitos are definitely bad this year! The hosts did leave out all sorts of mosquito repellents which was super because we forgot to pack our own, but we were bitten in the evenings as we sometimes went straight to a restaurant from the beach, or sat out on the balcony without reapplying repellent. Make sure to pack repellent and to use citronella.