Don't hesitate: just book it!
Sarah is a great communicator and made everything easy.
The flat is charming and very well located, perfect for the tourist in London, or for someone who is coming on a biz trip to the city and doesn't want to sleep in the middle of the towers. The nearby marina makes you feel like you're not in London but the views on the City on one side and Canary Wharf on the other side remind you that you're in London without the hustle and bustle. The balcony is fairly private and a nice breath of fresh air.
I was there on a hot day by London standards and the flat did feel warm but Sarah had anticipated that and left a free-standing fan that was very welcome. The entire flat was very clean! I would totally recommend this flat to anyone and hope to use it again in the future myself.