Only one word: perfect! We spent 5 weeks in the apartment and we enjoyed very much our stay in London. The apartment is very clean and cosy and the garden is fantastic! Geoffrey and Vicky are great hosts, they're very kind and helpful. Kentish Town is also a great place: it is very quite and you have everything you need (pubs, coffes, restaurants, markets and shops). The transport is great too: you have a lot of buses to the centre of London (only 3 minutes walk) and the Norther line (4-5 minute walk)!
I can definitely highly recommend this place and certainly we're coming back to their flat anytime we will return to London! We spent a fantastic time in Geoffrey and Vicky's apartment, we are missing it!