Great location in terms of accessibility (right by Union Square, so lots of Subway & bus options) & tons of food in East Village and other nearby areas within walkable distance. Also a Trader Joe's and Duane Reade less than 5 minutes walk away. Raanan's communication was also excellent.
Onto the apartment itself:
It's quite loud at night, with both traffic/sirens and people. Due to the window A/C unit, it feels like you're right at the street level. Also, the curtains are very sheer, so it gets bright early in the morning. We stayed for 6 weeks and didn't sleep well most of that time due to light and noise.
The couch/futon was extremely uncomfortable, so we never ended up using the family room to watch TV (instead it was comfier to watch in bed with our laptops). I'd also be aware that the futon is falling apart, so don't plan to use it as a bed (if you are booking for 3 people, check with Raanan if he can provide an air mattress or a replacement futon; this wasn't an issue for us however with just two of us).
There's very little storage so we ended up using our suitcases as "drawers" to keep clothes in (the provided chest of drawers is mostly ornamental and only good for little things/knick knacks, but not for clothes).
Wifi is fast but unreliable; usually I was fine working from the apt, but sometimes Zoom calls would drop and I'd have to hotspot from my phone instead.
There's a wash-and-fold right downstairs, which we used instead of a laundromat. Also keep in mind that there's no toilet paper, soap (hand or dish), shampoo/conditioner, etc provided, so be sure to stock up as soon as you arrive.
Overall, I wouldn't stay here again for long-term, but if it's just a few days, the convenience makes everything else worth it