We stayed two nights here. Jackie organised airport and port transfers for us, same rate as the taxis would charge but a better way to go as taxis can be hard to get when the place is busy with cruise ship passengers.
The studio is small, but adequate, and the view is superb. The steps, as others have noted, are quite steep in parts, but that's Santorini. Jackie organised a porter to carry our stuff up the stairs on the way out.
You're in the heart of Oia with its numerous boutiques and restaurants. You can't see the sunset from the studio, Jackie suggested going to Ammoudi to do this. It's down on the water and you can get there several ways. We caught the shuttle that leaves from the main square to connect with the ferry to Therassia for only 2€. Look for a black minibus, last departure is 1700. There a several appealing restaurants and we thoroughly enjoyed it. Getting back up to Oia means either hiring a donkey (5€ each) or getting the restaurant to call a taxi, a perfectly good Mercedes Benz, for the same price.
To sum up, you are in good hands with this host. Enjoy.