Great place and certainly a great concept! Everything is very good organised (codes to enter the building, vouchers for the breakfast...) and clean. For the noise it depends off course of the other guests (but there was no problem for us) and you are in the city so there is always some outside noise.
Overall it is the ideal place for a budget-friendly citytrip in Porto and you have an app from Mario to discover the city, which is very usefull!!