Decent - for a place to sleep for a couple of nights it was fine. Everything was clean, bed was comfy, all amenities worked etc. The area is nice and quiet so there were no outside noise issues, although the walls of the apartment are quite thin, and it is very close to other apartments in the building so you could easily hear other people talking through the walls. It's walking distance to Notting Hill so it was nice to be able to walk down to Portabello Road market and enjoy the area.
My only issue - It was expensive for what it is (to be expected in London). I paid a total of £250 for 2 nights, which for a small, simple apartment seemed too expensive. Outside of a place to sleep, it didn't really offer much else, so to me the price was too high for the experience. Without the high cleaning and service fees the price would have been more reasonable. All in all, it was a 'pass', and if you're using it as a place to sleep and nothing else it's fine.