I was in the place during a few cold days in Porto (mid April).
Pros:
1. the location is good. no very close to the Metro stations but close enough (about 10 minutes walking)
2. the design of the apartment is good, with a lot a natural light during the days.
3. has some basic facilities, but not all (look at cons)
Cons:
unfortunately I think there are more than a few cons with the place that can be fixed.
1. check-in. I arrived during 10:30 to the place. since there is no automatic code entrance and keys are required, I had to get them. they were left in some place nearby. but when I arrived they weren't there and we had to wait for about 60-75 minutes outside , tired, till Luis arrived with another pair of keys. some better solution should be found.
2. Electricity issues - the place has 2 heaters in the apartment , a heater in the bathroom (can be very cold there as well) and some basic facilities such as an oven or induction top to boil tea. even the smallest combination of those will make the electricity to go off in the entire place.
3. basic facilities are missing or in a bad shape - the blanket is all torn-up\ ripped , feels weird sleeping with it.. no Nespresso machine, just a single wine glass and unusable knifes . all of those can be fixed easily
4. hot water - the hot water goes off quickly, so you should manage it unless it is a really hot day. because heating the water and heating the apartment will cause the plug to jump.
5. during the weekend it can be noisy from the teenagers gathering around in the park downstairs (even tough the location is on the 5 floor)