Summary: Great flat in a great location, ideal for short stays. With a few minor details improved, it could be great for long stays, too. I would happily book this location again for future London visits.
Pros:
-Great location: at the end of a quiet dead-end street, easy access to Piccadilly line and major bus routes, plenty of delicious local cafes, etc.
-Co-op grocery store about a minute's walk away
-Clean
-Just the right size
-Nice shower
-Easy check in and very responsive hosts
Minor cons, all of which are easily resolvable I think:
-Unusually thick and hard pillows with unusually thin backup pillows. No spare pillow cases for the extra pillows.
-No spare bath or kitchen towels available
-Primary showerhead was clogged, making showers more tedious
-The flat was very warm in late September, even at night with the window open and fan on full power.