The biggest advantage of the apartment is location. It is safe, and entire building is residential and quiet - doormen look who enters the property and care about security. 23rd street is busy as explained in the description, so do not expect quiet nights, especially with the window open next to your bed.
Apartment looks better on the photos than in the real life - you can tell that this is old build and has it's years. Generally it is worn down. Do not expect to use kitchen to prepare large meals - it is good to prepare tea or coffee, or reheat some ready meal, maybe breakfast, but nothing more.
Marc is very responsive and easy to communicate with - transfer of the keys was very smooth and quick.
Overall I had a good stay but nothing special, the apartment seems overpriced for the standard and quality.