The place is amazingly well-furnished! It's simply gorgeous. It's an interior designer's dream.
The location is also incredible, right in front of the cathedral, with a terrific view of the Giralda.
The only problem for us was that they were remodeling the upper floor (heavy drilling and banging), which made it impossible to rest in the apartment during the day (which was a bummer, since the apartment is so gorgeous).
The remodel will be probably over for the next set of guests, so this might not be a problem, but it was a bummer for us.
Small issues: The fridge was set to freezing temperature, which created problems (froze our cheese!), and the container collecting the water from the dryer was not emptied: it took us a while to diagnose the problem and we had to download the dryer's manual to do that. Minor stuff, slightly irritating. Everything else was wonderful.