The host is great and very accommodating. This was our 2nd time staying in this apartment. This time we stayed for approx 3 weeks during the summer. We have a 2 year old toddler, so this review is from the perspective of parents with a small child.
While the location of the apartment is amazing for bars, restaurants, and for generally soaking up the Lower East Side of Manhattan, I would say it isn't ideal for parents toting around a stroller. The apartment is situated adjacent to a great deal of drug dealing/using. It's out in the open all hours of the day/night. Not a big deal I suppose for NYC, and we pretty much felt safe the whole time, but I can't recommend it in good faith for those with small children, especially if you have plans to walk around at night.
We were there in the full heat of summer. The bedrooms have dedicated A/C units and get very comfortable/cold if needed. There's no A/C in the bathroom. The common area, which has the kitchen, living area, and ample dining room table, has an A/C unit. During the day, the coldest the area would get was in the mid 80's, so that area was very uncomfortable during the day. At night we could get it to cool down a bit, but that area was definitely an issue for us, something to consider if you are heat-sensitive.
The apartment is on the top floor. Our toddler played in the apartment and pretty much be a kid, dance around, run, etc... This caused a disturbance to the downstairs neighbor who complained a few times to us. We felt bad about it, and tried to contain our kid as much as possible, but since he's a toddler it proved to be an issue for us.
So all in all, I'd say avoid the apartment if traveling with kids. I'd recommend it highly for say, a young couple or young group wanting to explore the Lower East Side for a few days.