This was our first Airbnb stay. We stayed at Gina and Ken's for 5 nights in the middle of a 3 week trip to California and they were the most enjoyable nights of our trip. Our party, myself, wife and two boys (7 and 5) really loved the house. It's as it appears in the photos, clean, spacious and incredibly well equipped. The kitchen allowed us to cook each night with fully stocked herbs and condiments which you take for granted when you're at home. We used the beach tents and chairs (we're going to get the same ones for home) which made our time on the sand and it was nice to sit out in the yard too.
The upper flat was occupied during our stay and as many have said you are able to hear some noise, we didn't find this as intrusive as others despite some small children being above, but I think it depends on your expectations.
The only request I made during the stay was whether there was a drying rack for clothing items that I didn't want to put in the dryer. Ken gladly provided one! Testiment to the approach that Gina and Ken both have in wanting your stay to be perfect.
I would certainly recommend staying at the flat and the Hillcrest area overall.