Hal's flat is in a great location. Five-minute walk to the Tube (Picadilly line). Lot's of pubs and shops within walking distance as well. My friends and I had no issues with loud music from upstairs tenants or noise from the cars on the main street; it was relatively quiet. The bedrooms were a good size. The bedroom with the full-size bed has a bathroom in it. The other bedrooms with the queen size beds share a bathroom. The kitchen was fully stocked with everything one would need to make a home-cooked meal.
Regarding check-in and check-out... Annie met my friends and me at the flat. We had arrived a lot earlier than expected, so it was nice of her to allow us to check-in earlier. We only had to contact her once during our stay, and she was very responsive.
I would highly recommend Hal's flat and will most likely return as I frequent London quite a bit.