Maria is a great host and made sure we were well-taken care of in her apartment. The location could not have been better (literally 15 steps from the front door of the building to the market) and after two weeks, we felt like locals. The reason to book this place is that it is clean and modern in a fantastic location.
The apartment itself is up 86 stairs, so make sure you're ready for that. Also, the apartment, and especially the bedroom is loud, day and night. As the other reviews have noted, at 5:30 the vendors set up their stalls and noise continues until after 1am from the bar downstairs (which is lovely and great for a drink by the way!). Make sure to bring earplugs as the window in the bedroom is single-pane.
Additionally, the wifi was very slow while we were there. We were getting about 5mbps download and about 0.5mbps upload which isn't ideal for a work-travel situation. Hopefully Maria improves this.
The one other thing is that mosquitos were getting in the apartment from somewhere and were a regular presence, leaving us with bites if we were hanging around.
Overall, if you want a modern apartment in the absolute best location and don't mind a couple minor inconveniences, then this is a good option.