I absolutely adored this lovely little flat, the foyer of this building is so beautiful, it is magical, the flat itself is a nice size and very clean with a nicely stocked kitchen. Great location, I had a lovely time.
I did have a few issues but I think they might not be such an issue for someone younger/fitter.
Firstly, the key is located some walk from the building itself, had I known what exactly this would entail I might have packed differently, as it happened it meant dragging my ridiculous bag around a VERY hot day and needing to ask a taxi driver for help. A backpack or wheelie suitcase might have mitigated the worse of the discomfort, but I didn't know about the distance until I was packed.

The WiFi information in the check in materials was incorrect, which was a terrible pain as I spent an hour trying to go by the materials until I eventually got the accurate details from the modem itself.
The wire was pulled out of the TV which meant it didn't really have a signal, I couldn't watch it at all.
I found the key pad impossible to use on the interior set of doors, the outside door was fine, but once I got into the second door, the key wasn't working at all, thankfully other people were around to help me get in.
These were not things big enough to upset my stay but had I been staying longer would have been a bit of a problem.