I can only recommend staying with Cristiana in her beautiful appartment. She is a generous host, layed back and very helpful, she recommended lots of nice places and sights in Porto. The room is very spacious, light and comfy and we had the most amazing view of the sunset. Having breakfast on the terrace in the morning was delightful in the nice weather. The flat is also quite close to the old town, only a 20 minute walk away.