Myself and two friends stayed at Tatiana's apartment in the Old Town. The apartment is fabulous and you just could not get a better location. Tatiana is a great communicator :-)
I rated the overall experience as a 3 but everything else as a 5 as the noise level from the street appears amplified in the apartment - perhaps it is because of the narrow street it is on.
I would most certainly book the apartment again but my advice to anyone booking is to bring really good ear plugs - we bought some and this made the second night more bearable.
Lots of Tapas bars on your doorstep to try out. Our favorite little eatery was the 'BioMio' around the corner - great for breakfast and lunch. Also the restaurant next to it if you like fish 'Il Pesciolino'.
Seville is fantastic with lots of super historic places to visit. Enjoy :-)