Myself and my partner's stay at Davide's apartment was fantastic.
The apartment is bright, spacious, airy, and very clean. It has great views of the Venice canals from the living room and kitchen windows - it was really great to start each morning by looking out to that view. There is plenty of room in the bedroom and living room in particular; the galley kitchen is smaller, but you would have no problem cooking a meal in there (although we didn't). The shower was powerful and hot. The only slight negative with the apartment itself is that the internet connection did not work properly, so we had to use our mobile data plan. If this would be an issue for you, I recommend contacting Davide to check whether this has been addressed.
The apartment is located about 5 minutes or so walk away from Santa Lucia railway station and less than 5 minutes from the Piazzale Roma vaparetto (water bus) station. It is quite a distance from the main tourist sites around San Marco, but that suited us fine- we wanted somewhere quieter. Leave plenty of time for travel between the apartment and San Marco, as the vaparetto can take quite a while (30 mins?) and walking might take you longer as you will constantly stop to check directions around Venice's maze of picturesque alleyways, footbridges, and concourses.
Communication with Davide was fine after we booked the apartment. He then put us in touch with his brother Luca, who would meet us at the train station and walk us to the apartment. Luca gave us some great tips when we arrived at the apartment, regarding things to do and see, and areas / places to go to eat and drink. We contacted Luca for some more tips during out stay, and he was more than happy to oblige. Some of these are within easy walking distance of the apartment (some spectacular churches nearby, and there are also some great non-touristy places to go for a drink and/or something to eat).
We would be happy to recommend Davide's place to others, and we would stay there again if we return to Venice.