Amazing location - you really are within walking distance (say 20 mins) to a lot of places (Flatiron, Madison Square Garden, Union Square, Macy's) with a drug store around the corner for all the essentials. The subway stop for the 6 train is also really close.
I walked back on my own at night a few times and felt very safe.
For the apartment itself - a decent size and would be large enough for two people without stepping on each other. Most importantly, the bed is super comfortable and the skylight over the bed is a lovely natural wake up!
The 3 flights of stairs are quite steep, so as long as you are prepared for that it is all good.
Check in was also super painless - which is what you need after 20+ hours flying time!