The flat is very bright, comfy and central: underground piccadilly line from Heathrow direct to Russelsquare, 200m walk to the flat. It so central that it allows you to reach London center (Soho, Covent Garden, Camden Town, Hyde Park, Shoreditch, Clerkenwell...) within 10-30min walks. Perfect! King's Cross is 5min. there's everything you need in the kitchen, wifi does work, good temperature in the flat, comfy sofa.
You got a delicious small french Bakery, around the corner.
If you're not used to live in cities, bring your earplugs. No bad surprise, flat according to the photos. No problem for the keys and the check-in/out. I strongly recommend !