Miguel and Rui were excellent hosts. They met us at the metro stop near the apartment, then it was a short walk.
Miguel emailed me excellent instructions to get from the main train station to the nearest metro stop next to the apartment. They were very helpful with suggestions of where to eat, some Portuguese dishes we might like, and places to go and nightlife to check out.
The apartment is located in Vila Nova de Gaia, and is very close to all of the Port Wine Houses, but is a good walk to Porto downtown. If you're mainly interested in visiting and tasting port wine (like me), then this is an excellent location. If you want to mostly visit Porto, you may want to check other listings. On a map, it doesn't look far, and it's a very short ride on the metro (2-3 stops), but if you're walking, it can become a long distance because Porto and Gaia is VERY hilly. Be prepared to get some exercise in and wear comfortable shoes.

Pros:
Located very close to the Port Wine Houses in Gaia and all the river tours.
Close to a metro stop.
The apartment was very clean and comfortable, and it has 2 full baths.

Cons:
Located at the top of a hill.
No A/C (I didn't need A/C while I was there, but this could be an issue in the middle of summer).
Other:
There was shampoo, but no bar soap.

Overall, I enjoyed my stay here. I also didn't have a issue with a late checkout. I'd recommend this place to friends.