We really enjoyed this flat and I think best to break it down into three reviews:
The Place - We really liked the place. It is underground, which is different, but it was spacious, especially for London, and well stocked. It is right under the reception so you constantly hear footsteps and chair on the tile above, but we got used to that eventually. The proximity to Hyde Park and Paddington made it super convenient and being so close to Queensway meant there were lots of restaurants. We also walked to covent garden, soho, chelsea, and belgravia from our place. Really great.
The people - The people who work at the hotel/flat are great. The folks at reception are fantastic people who really care about your stay. We thought the clenaing crew did ok and could have been better.
"Alex" or booking agent - I believe "Alex" is actually an agency that rents flats around London. It really did not bother us as their communication was fine but sort of just wish there was more transparency on who we were actually talking to.