Porto is probably my favorite city so far. I would go back again in a heartbeat. Great friendly people, fabulous wine, wonderful food. Really easy to get around. We got a cab from the bus station to our apartment, and we walked everywhere from there. They have a beautiful train system, but we never used it. Took a cab to the airport when we left.
A really picturesque old city. They have a lot of buildings that are uninhabited, and self destructing, but they also have a lot of construction and repair going on.
Our most memorable day was a trip across the bridge to Gaia for a little sampling of Port wine. Lots of fun, really good port, beautiful day. What more could you ask for?
Since I am finally getting around to writing this from London, I can say with confidence, that in Porto you can buy much better food, wine, lodging for less than half of what you will spend here, and they dance in the square in front of the old cathedral. Oh yea, there's also about 8 million less people than London.