In general, our stay was excellent and our hosts extremely friendly. The location is top-notch.
I'll focus here only on the negative. IMO, the place had two major drawbacks.
[1] Noise. From two directions – the internal patio (i.e., your neighbors in the same building) and the street. The windows are single-pane. You hear every last word from your neighbor's TV, and there's never a respite from sirens and motorcycles along the major thoroughfare. Bring the best possible earplugs for use whenever at the apartment.
[2] The alternate sleeping arrangements. There's one nice bed. But the futon couch feels like two side-by-side cots – short, narrow, and concave. And the sofa bed's thin mattress is completely wrapped in a thick plastic encasing – uncomfortable and loud. (I opted for the futon.) An easy mitigation would be adding another real bed.