We had a fantastic time staying at the ORM Cristal Apartment and would highly recommend it - it is a very cool modern building that is well located - close to the centre of the city and has everything you need including a small kitchen, washing machine, and plenty of space. Favourite part was probably the balcony - a perfect spot to have breakfast in the morning or a drink in the evening. Igor and Tânia were both extremely helpful and offered to arrange things we asked about in the city. Would definitely recommend this apartment and will stay here again next time I'm in Porto.