The Phoenix House is unlike anywhere we've ever stayed. Definitely an unforgettable experience! It's a tiny house out in the middle of a lava field, with just a few other houses around. It's got all the amenities you'd expect and even a few extras (coffee, French press, beach gear). We thoroughly enjoyed our stay!
While you're there, we highly suggest getting breakfast at Pele's Kitchen in Pahoa. It's close to the house, and it was one of our favorite meals on the trip.
A couple of things to note — it's 40 minutes from the closest "big" town (Hilo). This is the nature of the Big Island, things are further apart than you might expect. It's a convenient location to stay if you're visiting Hawaii Volcanoes National Park and/or driving the Red Road, but otherwise, there's not a whole lot nearby.
Also, the house doesn't have AC (seems standard, none of our Airbnbs did while in Hawaii) and can get quite warm once the sun comes up. It wasn't too bad at night with the fans on.