My girlfriend and I stayed at Claudia's loft over New Year's and were quite satisfied. The loft was clean and cozy, but for some reason seems smaller in person than in the pictures. Plenty of room for the two of us though.
Claudia was very nice and easy to communicate with. She answered quickly to all of our inquires and helped us book a cab for our ride to the train station when we were checking out.
One thing that is important to note is that this flat is NOT for the light sleepers. The loft is situated right next to the train tracks with trains driving by every half hour around the clock. Other than that, the neighbourhood is lovely, and we will definitely stay in Navigli again the next time we go to Milano.
All in all, a very good place to stay for the price - but make sure to bring your earplugs!