We had a great stay in London! The apartment is well located, walking distance to Regents Park, Marylebone High Street, and Paddington Street Gardens (which has a nice playground for kids) as well as various tube stations and bus stops that connect you everywhere. The apartment is on the small side but it's well organized and clean. We had everything we needed to be able to make simple meals and wash some clothes. Note that the apartment is on the second floor and there is no lift, but the steps are small so it's not so much of a struggle upstairs with luggage.
Our host's son, Denis, waited for us to arrive from the airport (which took longer than expected), explained all the details and kindly made another trip over to install the router and bring an iron. He even bought us some fresh organic milk knowing we were bringing our toddler! He was available throughout our stay to quickly answer questions.
I would definitely recommend this apartment and thank our lovely hosts for a memorable stay!