My partner and I stayed at Silvia's apartment for almost 3 months over the Summer and we loved it!
The apartment is very small but pretty much what we expected. Space wasn't an issue for us because we spent most of our days exploring anyway. The proximity to Central Park is ideal (only 2 blocks away) and it gave us a reason to exercise in the morning. The 72nd St Subway Station is just around the corner and being on the express line (2,3) was great because it made getting Downtown much faster and easier. The kitchen was very well equipped and had everything we needed for a night in. There are also some great supermarkets within walking distance (Trader Joe's is across the road and Fairway Supermarket is only a few blocks away). The apartment does not face the street so it was surprisingly quiet at night - we couldn't hear any outside noise at all. Although as others have mentioned, the mattress in the loft is very thin and may be in an issue if you have shoulder or back problems.
Overall, we really enjoyed our stay here and would book again in a heartbeat!
P.S. If you do end up staying here and are after a decent cup of coffee on the Upper West Side then we recommend Box Kite - just a block away and they do great espresso.