Mary is a great host. Quick with responses to inquires. Fair prices on her units. The units are VERY clean. They come stocked with linens and shower amenities. The kitchen has everything you need for your stay.
I would note that all the beds, while comfortable, are doubles and not queens. I also breezed past a review from a traveler saying their is no "commons area". I didn't think much of it until we were there. The only TV the unit has is located in hallway like area with no where to sit. If you are sightseeing all day this is not an issue, but we have a small child that naps. So it was kind of hard being tied to the apartment while they slept and we couldn't comfortably hang out anywhere else besides a bed.
Lastly, the neighborhood is okay during the day. But once night hits there is a good bit of police activity and police sirens. We stayed inside mostly in the evening so it was okay for us but if you plan on going out late, I would take this into consideration.
Overall I recommend Mary's place. It's reasonably priced, clean, and a quick T ride into the city.