Ana is one of the sweetest, kindest, most generous people I have ever met. I'm glad that I stayed at her place and hope that we remain friends. Ana did more than just recommend some sites she took me to several. I can't promise that your experience will be the same, but you get the idea.
Her place is located across the river from the old part of Porto. Depending on who you are, this can ge a good thing or a bad thing. If you're 20 and want to be in the center of the hubbub, you should maybe be in Porto proper. Hubbub = proximity to the oldest buildings and vibrant nightlife.
If you value a little quiet, calm, then Ana's location can be great. Porto is a short bus (or car) ride away. Ana's location is secure (large building with a doorman) and located close to two shopping centers. I liked that supermarkets, gym, etc. were all nearby. The marina (super beautiful) is easily walkable. You can also walk all the way to Porto and back over one of the bridges. That's a multiple-hour adventure for those who really like to walk.