Jacosta was a great host and we loved staying at her place (we booked it in order to participate in the Rottnest Swim, so the location was ideal - allowing us to walk down to the start on the morning of the race, as well as get a few practise swims in at Cottesloe beach beforehand). If it's available next year, we will try to book it again.
The place itself was very tidy and rustic - it felt far more like staying in someones home than a holiday rental (which is not surprising, as it is Jacosta's home). The neighbours (that we met, anyway) were very friendly. If you're after a nice relaxing place, within walking distance from the beach and restaurants in Cottesloe, I'd definitely recommend.