For starters - the location of the apartament is really perfect - you'll be within 10-15 mins walking distance to all important stuff in Porto, as well as Trinidade metro station if you decided to explore :)
The apartament is managed by company that specializes in that. They don't mention it in the description, but you're going to have to pick up keys from one of their 3 locations in Porto - and it's 10 Euros if you wanted to have someone meet you outside apartment with the keys. I can't say anything more about check-in besides that it happened - just guy giving out the keys. On positive side - you can leave your luggage there while waiting for check-in.
As for apartament, as mentioned in other reviews - there's a lot of noise coming from the street (day and night). But, there's also noise coming from the hallway and staircase - you'll be hearing everyone talking or coming to their apartment, especially at night. Stairs itself are pretty steep, so it may be hard for people with big and heavy bag.
Apartament's size is perfect for 2 people (if you want to eat out a lot and sleep there mainly). Unfortunately, it is not clean. There was dust on drawers and kitchen table legs and tile joints in the bathroom would use some really good cleaning, as they're simply dirty.
As for the kitchen itself - there was no dishwashing fluid in the apartament, garbage bags - only the ones already put in, nothing for change(and our stay was from Sunday to Friday). No salt and pepper. If you want coffee/tea - only two mugs, looking very questionable inside.
Push-to-open closet door don't work, so it's a bit of hard time accessing that.
All-in-all, stay was okayish, but next time I'd rather book something from local people instead of Porto Concierge.