This flat is excellent! The bedroom and living room are very spacious and the bathroom has been recently updated. I slept on the couch which was long enough for my 5'9 frame, flat, and firm.
We didn't bother with the metro during our stay, but the flat is about a block from one bus station and maybe three blocks from another. It's not a bad walk to Kingscross/St Pancras, though I wouldn't recommend it if you have a lot of luggage.
Check in/out was incredibly easy and convenient, and the directions to the flat were detailed and helpful, even including useful information about the door latch's quirks.
After a pretty cramped hotel room in Paris, staying here felt amazing! There was room to spread out, and it was so homey. This was my first airbnb stay, but I will definitely be doing more!