Great location very close to the train station, shops and restaurants and Hampstead Heath. We stayed during a period of very hot weather, and the apartment got really hot without air conditioning (this was expected) and limited airflow.
The cleaners didn't do a great job, with the apartment being quite dusty and glassware not having been washed properly. However, we did get an offer for cleaners to be sent over during our stay which was appreciated.
The school outside can get very noisy which may be an issue if you stay home during the day.
Finally, there is a nice rooftop area with a great panoramic view of Hampstead and London.