Paola's apartment was marvellous - very central in the Old Town so we could easily get to everywhere we wanted to visit, and exactly as described. You do need to be OK with stairs because it is on the 3rd floor. She was very flexible in allowing us to check in a little early and check out a couple of hours after the official time because our flight didn't leave until late evening.
The pedestrian area outside the flat is quite noisy in the evenings with people enjoying the restaurants and tapas bars nearby - this didn't bother us at all, but if you like compete silence after 11pm then this might be an annoyance.
We loved Valencia, and if we return we would definitely book this apartment again.