Owl's House is very true to the Airbnb concept. You definitely feel like visiting a private home – in the best sense of the word. Very comfortable and with a lot of character. In particular the large living/dining room is lovely with a beautiful view over the roofs towards the harbour and mountains.
The apartment is perfect for 2 x 2 guests. Be aware that one of the two bathrooms is not on the same level as the bedrooms (as mentioned in Jonathan's description).
The location doesn't get much better in Port Sóller: Bars, restaurants, supermarket, pharmacy, ATMs, taxi, tram (to Sóller) etc within 5-10 minutes walk.
Our only real issue with Owl's House was parking. We searched for an apartment with free parking. In theory there is free parking on the street. The problem is that it is impossible to find an available space. Due to construction work on the harbour site 150 (hundred and fifty!) parking spaces are temporarily blocked. None of the locals we talked to had any idea how long this will last. The remaining 30 spaces are occupied by local residents and restaurant staff. So, don't bring a car to Port Sóller or be prepared to spend €8 a day in the parking house 15 minutes walk from the apartment. Be aware that payment in the parking house is coins only. No bills or cards! Incredible!
That said, Owl's House is probably the best value for money Airbnb in Port Sóller.