Residencial Portuguesa is good if all you want is basic en suite accommodation at a very reasonable rate (i.e. a bed, a toilet and shower) within walking distance of the old town centre (it is only about 5 minutes’ walk from the Clerigos Tower). The bed was comfortable enough, and the bathroom - although extremely small - was (like the room) clean and had a good shower with plenty of hot water.
But do not book this place if you want any 'luxury' or a quiet night. Examples of the basic facilities were: there was no heating or air-con, the 'free toiletries' were one small bar of soap and 2 sachets of shampoo (for 3 nights), I had no room service, the TV screen was smaller than an A4 piece of paper, there was only one socket available in the bedroom (which was loose!), there was no wifi, and there were no blackout drapes/curtains (as described in the listed facilities).
The main problem I had with the room was with the noise from the local area (I stayed at the weekend so maybe it's quieter in the week?).
Last point: I wish that you were given a key to the outside door instead of having to ring the bell to be let in every time you returned to the place. (Having said that, there was never any delay waiting to be let in, and they were also very helpful in letting me leave my bag for a few hours longer after checking out).