César was always responsive and available. He speaks English very well, so communication was never an issue. He even recommended me where to see in Porto. Overall, he is a very good host.
There are 6 rooms at total in the guesthouse, so there were other guests as well. But I rarely saw or heard them. The bathrooms were not always perfectly clean due to the usage, although they were always clean enough.
For the price, I'd say it's a very good deal. If I come to Porto again, I would again stay here.