We stayed in Carmens apartment for 5 nights over New Year - and had a great time. The apartment is small, but convenient, the location is great, there is a balcony (but if you do not like heights, this is not for you: 13th floor.....), it has all you need for a short term stay - even a card for the sube transportation system, which you can just top up with what you need.
We really enjoyed ourselves - and were grateful that Carmen stayed up till after midnight to greet us in the apartment.