I stayed at Nady's place twice, for 10 days and then for another week and it was very nice. The location is very good, about 20 minutes walk to Kings' cross train station. If you like to walk it's not far from central London- about 30-40 minutes walk to Oxford street, Soho and that area. If you don't like to walk then the train is, as I said, not far.
Nady and his wife are really nice. You have everything you need- Wifi, bathroom (which you share), shared kitchen that you can use with a fridge, microwave, stove... Good place for long and short stays.