Kevin is a very responsive, kind host. He kept in contact often and wanted to make sure that we got in okay. His availability made me feel very welcome! He even helped suggest an alternate route to Hakone since we were hoping to take a taxi there (note: don't do that from Hatsudai). Everything we needed to know was laid out well in the information email.
For those traveling with a JR Pass, please keep in mind that the Hatsudai station is not included since it's a subway line. Just get a Pasmo card and it makes it way easier to get around. It's just one stop from the Shinjuku station, so it was very convenient! On top of that, it was easy to get to the 7-11 down the street, as well as a couple of drug stores. I got sick during this trip and was easily able to procure the medicine I needed.
My housemate and I are pretty small, so it was fine for us, but keep in mind that it is a very small Tokyo apartment. If you're on the taller side it might be difficult.
A good place to knock out at the end of the day when you're done with a night out in Tokyo if you're okay with that extra stop. Do keep in mind that the Shinjuku station isn't very luggage friendly - if you've got heavy luggage, expect to still take a few flights of stairs before finding an escalator or elevator.