Stayed here with three adults and two toddlers; it was an amazing find. The upstairs deck is definitely set up for entertaining, but also made for a great place to have dinner with a few friends with some truly gorgeous city views. The neighborhood is fantastic for small kids: great restaurants and cafes on 5th, frequently closed for street markets, and the playgrounds and parks are just stunning. Steps to the Union subway stop (and not too far down the street from an elevator-equipped stop if you can't get around the need for a stroller), just about walkable to Brooklyn Bridge Park.
The apartment is everything you want when traveling with young kids: hip and chic but also wide open for easy sight lines, a well-equipped kitchen, nice washer-dryer, a tub, and just enough decor to make it adult-friendly without taking more than a few minutes to (generally) toddler-proof. Be warned that the stairs in and out of the unit were tall and steep, so shlepping a stroller up and down from the street is a hassle, but the host cheerfully helped us find a place to stash some things on the ground floor, which was a lifesaver.
The host was INCREDIBLY responsive, quick to answer questions about the unit and the building, and just generally cheerful and accommodating.
Getting two hotel rooms in the area would have cost us at least as much as this place and wouldn't have been nearly as great an experience. I was a little worried when we booked it that this would be too chic for a family with young kids; don't be. This was an absolute gem, and if you're traveling with a family and are lucky enough to find this place available, I strongly recommend you jump at the chance.