From the front it has an inconspicous awning and tinted double doors. Inside the doors is a nice bar/cafe area, then beyond a sign telling you to wait for your seat. Remember, the Portuguese are a lovely people, genuine and friendly, but they do things in their own time. They don't mean to be rude, but if you are not running at their pace of life (and lovely it is), you could take offence. But be patient!
One time convent, one time brewery, the main area is a high ceilinged dining area with the most amazing tiling on the walls. Unfortunately this is now the smoking section so non-smokers are relegated to the equally large but much less charismatic room beyond. Through that, on the right is a courtyard. The staff are great, mature gents with good advice and a lovely manner. The portuguese eat here, it is family friendly, but you also come for the food.
The prices are what you expect from Lisbon, very reasonable, in fact they have a daily special for €5.90, which is fantastic in terms of quality and price, usually a local speciality. The rest of the menu is typical portuguese, fish, pasta, something for everyone.
This place has it all - location, staff, environment, quality, and price.