Absolutely loved our stay in Juan Carlos' place! It's just (I'd even say even more) beautiful than in the pictures. Juan Carlos was a great host who was extremely easy to communicate with. Would happily stay at any of his places in the future!
The location is fantastic. It's quite central - close walk to a major bus and train station - but also is on a quiet, quaint, adorable street that is a quick walk from the nightlife hub. So whether you're after something quiet, or looking for a bit more oomph, you can make it work for you. It's also ridiculously close to both the Seville Cathedral and the Alcazar.
Just a note - if you're staying in winter, pack house slippers. It is a 500 year old house and even with the updated amenities and heating the non-room floors can get a bit chilly.