Great flat in a great location.
The outdoor space is quiet and fantastic to enjoy breakfast or evening drinks in.
The 'upstairs' is a low-ceiling mezzanine which requires climbing a steep ladder to get to, not a problem if quite fit, but could prove a problem for those less so.
We only had one issue while there - an embarrassing inability to find the cutlery drawer, it's quite stiff and doesn't look like a drawer under the hob, which someone quickly came out to show us.
All in all, a great flat and a lovely stay in Porto.