We stayed at this place for a week with our two children. It was a budget holiday and we brought along blow up air beds for the little boys. We used the washing machine to refresh our clothes as we had only brought along our free Ryanair allowance! The bed was comfortable, the location is unbeatable right in the heart of the city, only tens mins walk to Sao Bento station. We used the metro and the buses to get around and found Porto absolutely delightful.
The flat struggled a little to cope with the four of us, we had to be careful not to use too much hot water and at one point there was a power cut and the electricity box had to be restarted. This was quickly sorted. Our host was very helpful.
We loved Porto and found that if you venture out of the main tourist hotspots and look for restaurants where locals eat, there are many budget options.