Mark's place was easy to get to from the major transport hubs. I read a few reviews that state the neighborhood is bad, but would disagree. The shops were all friendly and there is a school right across the street. Noises like people yelling and sirens are to be expected in any city. At no point did we feel unsafe.
I believe this place is targeted at younger folks or couples who plan on spending the vast majority of their time enjoying London, not hanging around the flat. If that's you, then this spot will suit you fine. If you're looking for a 5 star hotel, go spend $800 a night.
The place was clean on arrival and Mark was quick to respond any time we communicated. There were a few minor issues we had, but overall our stay was as expected and I'd recommend this spot as long as your expectations are realistic.
I'll also add that while not in the city center, there are plenty of good places to eat around the area, and almost everything is either within walking distance, or a 30 minute bus ride away.