I stayed in I Felzi for 6 nights for work related purposes (4 days) and leisure (2 days) and it was the perfect place for me. The apartment is renovated perfectly with nice bright coloured materials, providing a very cozy and homely feeling. I found all facilities mentioned in Roberto's advertisment in perfect working condition: the airconditioning was a necessity with the hot weather, wifi worked perfectly, availability of a washing machine was a blessing, etc.
Also the location is really great: a very quiet area away from the tourist area to escape and relax after a long day. There are several very good (not touristic) restaurants and a small supermarket just a few steps/minutes away. Access to the waterboat to/from the airport, as well as a major stop for public watertransport is just 3 minutes away which makes it easy in case you want to move around by boat or visit the other islands. Even if you want just to walk around Venice, Rialto bridge is just about 10-12 minutes walking from the appartment, San Marco square about 20-25 minutes.
But most importantly: the very warm welcome by the owner! Before my trip Roberto provided me with all necessary info such as how to get there from the airport. Due to his job he was not able to welcome me personally, but instead his daughter Ludovica took very well care of me by meeting me at the quay where the boat from the airport docked, accompanying me to the apartment and showing me how everything worked. Whenever I needed to know something either of them replied to me in the shortest delays. I appreciated very much being invited by Roberto for a coffee and short walk on Saturday morning. It was really a pleasure to meet and talk to him and his wife, whom we accidently met while walking around :-)
In short: if you travel to Venice as a couple (or alone) I would definitively recommend staying in I Felzi, which for me is the perfect place to stay in town if you are looking for what I described above.