Stayed for 2 months. Everything was as described, and Matt lives upstair so all the request would be handled very promptly.
And as described in the post, the unit is right next to the Metro line. Though it was very convenient, it's quite loud and you can literally feel the vibration, but I got used to it after a couple of days.
All in all, it was a really good experience, apart from some plumbing issues towards the end (it was not the hosts' false really). I'd definitely stay there again if an opportunity arises.