This is a top-quality set of apartments, in a great location. We have stayed at many airbnb places, never before have we been able to tick all seven of the "special" boxes. The apartments were stylish, incredibly clean, fully equipped and comfortable.
We used all three, so the middle one (the "house") was our meeting/social point, but they would all work well separately (or you could use two), depending on your needs - each is fully equipped, and although each is slightly different in layout, there is not much to choose between them (i.e. they are all great).
Marcello is a wonderful host - communication was brilliant beforehand, and he even came and picked us up from Siracusa bus station, before personally showing us the flats and telling us lots of useful local information.
If you're looking for high quality accommodation on Ortigia, you need look no further.