First things first: the location is absolutely unbeatable. Also, I felt so posh coming in and out the front door in such a coveted neighborhood ;)
The apartment itself is lovely. Spacious (which is surprising, in London) and cosy. It's underground, so it's not so bright during the day, but a) I was there in November, so it would have been dark very early anyways, and b) I slept like a log during the night. The bed is also super comfy, and there's plenty artificial light (lots of lamps and ceiling lights!). I stayed at the studio for 8 days, and felt at home the whole time. The only inconvenience of a longer stay is that there's no washing machine, so I had to improvise (but that's on me, I forgot to check beforehand). All in all though absolutely recommended. Oh, and at a great price!