Alberto is an incredible host - we kept him waiting with a travel snafu on our end, and he still made the time to walk us through the unit and give us neighborhood info. Very gracious, very accommodating, very easy to get in touch with.
The unit is a cute 2BR in what the internet tells me is sort-of-Triana. Not quite the heart of the barrio, and across the river from a lot of the usual sights. Definitely close enough to everything to be convenient, but just far enough away to not be in the thick of it. This was great for us. The washing machine came through clutch at the tail end of a long trip, the beds were comfortable, and the bathroom did the job. We literally used nothing else in the apartment, so no comments on that front.
If you're looking for low-key, clean, quiet, well-appointed, and convenient accommodation in Sevilla, I strongly endorse staying at Alberto's property.