I spent 3 nights in Kathe and Lisa's apartment with my boyfriend in August and I am really happy for this choice! Also considering the extremely high prices of hotels in Boston, I can say that this is a very good and convenient place to stay in Boston. Located between Back Bay and South End, walking distance from Back Bay subway station, in a quiet street in a very elegant neighbourhood. The house, as you can see from the pictures, is the typical Bostonion style. It contains private apartments which are completely independent one from each other.
Our apartment was on the 2nd floor, on the top of a few stairs - nothing bothering but just to let you know in case of heavy baggage. The bathroom was clean and the shower head was really powerful. In the kitchenette there are tea and coffee machines and the hosts put beverages and yogurts in the fridge to allow us to have breakfast there. The apartment was fresh and we didn't need to switch the ceiling fans on.
Last but not least, Lisa was a great host: we never met but communicating with her has always been very easy and fast and she facilitated us for both late check-in and for leaving our luggage there after check-out.
Overall, I think this apartment has the basic characteristics and can be the right solution for a good stay in Boston!