Carlos's place is probably one of the most luxurious and charming places we've stayed at on AirBnB (and we've stayed at a lot of places). All the furniture and appliances are super high quality, the bed was phenomenal, and the decor is even better than in the pictures. The apartment is located at the absolute center of the historic quarter and the river is less than a 5 minute walk. All the metro and bus lines are also 5 minutes away so it's easy to get anywhere else you need to. The only downside is that it can get loud on Friday and Saturday nights from the people drinking on the street, but the bedroom is in the back and shelters you from the noise. If you're super sensitive to noise, you might want to bring earplugs, but we didn't have a problem with it though.
Overall I would recommend Carlos's place and he's a very friendly and knowledgeable host who really takes care of his guests.