I stayed at Matt and Gemma's place for about ten days in July. The flat is wonderful for a number of reasons. First is the location: it is literally two blocks (200 meters) from the Finsbury Park Underground Station, giving excellent access to just about anywhere in London. The neighborhood has lots of conveniences just on the flat's doorstep - restaurants, grocers, coffee houses, pubs, etc.
The flat itself is extremely comfortable and inviting. For a London flat, it is quite spacious, and even has the rare addition of a garden patio, which I used on a number of occasions.
Matt and Gemma are wonderful and gracious host. On arrival, they had a bottle of wine, some cheese and fresh bread for me. They were very flexible regarding both check-in and check-out. They even allowed me to extend my stay when my other arrangements fell through at the last minute.
I cannot say enough good things about this flat or its owners and wholly recommend it to anyone interested in spending any time in London.