I can say many good things about the flat itself - it's spacious (we were four adults and one child), it was tidy and clean when we entered, the flat was warm in winter (although the windows in the rooms weren't double glazed, the heat worked fine - we had even an extra electric heater just in case), the toilet was nice, spacious and comfortable and the shower worked well overall, the living room was very spacious, etc. But the best thing is its centrality. It's my second time in London - previously I stayed in Chelsea, which I found relatively central. But this flat is truly at the heart of Westminster. Literally at a 2-min walk to the Palace and very close to many touristic attractions in the city. At the same time, it's not in a crowded street but in a beautiful sector. We loved it and truly recommend it!
Thinking of downsides, I'd mention the creaking of the wood floor. It was sometimes a wee annoying (we have a one-year-old baby with us sleeping), but it was not a problem ultimately, to be honest; and in my 4 years in the UK, I have never been in a flat whose floor doesn't creak - haha true story!
The other downside that comes to my mind is that the glass screen of the shower was a bit loose. But surely it's something minor and fixable.
Great place. Comfy, spacious and central. Really recommendable.