As an avowed fan of AirBnB, I'd be pouncing on this in London - there's such a number of interesting places listed these days, and I have a number of contractor friends who swear buy it when working in London.
While King's Cross is up-and-coming and a good transport hub, the area's general seediness is not fully gone. Nothing to be overly concerned of - it's certainly not the place it was 30 years ago - but do be aware.