We ate here both nights of our stay in Coimbra because we loved it so much! There is also a lot of choice so you won't get bored.
Here you choose a meat/fish, then choose one of boiled potatoes/chips and one of vegetables/salad. The vegetables consist of nicely cooked cabbage and peppers with some oil and raw onion, and the salad is simple and undressed which works really well.
All the meat and fish is grilled, and presented at the front of the restaurant for you to see. The menu changes each day but generally speaking they have salmon, sea bream, prawns, squid, bacalhau, horse mackerel and swordfish; then they have ribs, pork belly and other cuts of pork, some steaks and sometimes veal, and chicken. Some of the meat options are very cheap (5-6 euros) but we thought the fish looked better and chose that on both nights. For a rough idea of cost, the sea bream was 10 euros, the bacalhau 11 and the squid 9, all including the sides. These were the dishes we tried and they were all delicious and plentiful.
We would recommend asking for bean-rice, something that we saw others had but didn't seem to be on the menu. It was rice in a red sauce with kidney beans. There are olives, bread and butter and sardine pate provided to start, though if you eat them you pay a small charge for them.
The staff are welcoming, though with varying levels of English so you may need to be clear about what you want. There seem to be both tourists and locals alike enjoying this restaurant and it has the feel of somewhere that is really popular locally. The restaurant has plenty of tables so there is no need to reserve for two - maybe if you are a larger group.