The apartment was nice, well presented, and generally comfortable. The bed was very comfortable and it has a great shower, so that makes it feel very homely. The location was pretty good (a good 15 minute walk to the station and shopping area). The nearby shops and the local pub are pretty good too.
Unfortunately there were two main things that prevent me from recommending this apartment in winter. Firstly, the heating is controlled by the main house, which is fine, but they only have the heating on for a few hours in the morning and a few hours in the evening. No heating during the very cold nights, and I had to leave the apartment each day (thankfully there is a great co-working space nearby, but it was costly). There is a small electric heater but it's not one that you would feel safe enough to leave on overnight or for the whole day if you want to work from the apartment. Thankfully the temps didn't drop as much as was expected and the bedding was warm, and with some extra layers on, I was not too cold, but it was just an unnecessary worry when just leaving the heater on would work better.
The second issue is that the kitchen / entry area has a vent to the outside which lets in all the cold air, so you need to shut the kitchen door to keep the heat in, which makes the kitchen off limits because it's just so cold in there.
I'm sure it would be a lovely apartment in the spring or autumn when it's not so cold.
Other things that would really improve the apartment are a bigger TV, a better hairdryer, and a side table by the bed.
Apart from the worry about the cold I did enjoy my two weeks in Hammersmith.