Natalia's place is a real treat. Location is great -- as other reviewers have noted, easy access to both Holland Park and Notting Hill Gate tube stations. I'm a walker, so if you're into that it's also perfect for walks of short length (to Holland Park), moderate length (Kensington, Hyde Park), or even a bit longer (I walked to Primrose Hill via St. John's Wood one day, home from Westminster Abbey another).
Flat itself is both homey and stylish. For being so close to the "action," it's also remarkably quiet -- I slept with the windows open, and there was almost no street noise, even on a weekend. A beautiful building and street.
Natalia was always quick to reply to messages and very accommodating.
Great value, highly recommended.