I agree, O Manjar and Annas are both great restaurants.
We also go to Alfredo's, which is on Rua do Telecommunicaos, just behind the Town Hall, about five minutes from Cerro Alagoa and Brisa Sol hotels. Great for fish. For steaks we go to Fabio's, which is on Rua Fernao de Magalhaes in the Cerro Branco area. Also behind the Town Hall, turn right just befor you get to Alfredos.
Next to Fabios is Doce Diner if you fancy a bit of well cooked British fare in a really nice restaurant - no smoking inside, but you can light up on the terrace.
For chinese, we go to Chinese Fu, which is directly behind the town hall, and for Indian, The Minhar, which is just off Music Street, close to Fishersmans Beach in the Old Town, or India Nights, which is just past the western side of the main square, Just off Rua 5 Octobre.
All good value and serve great food.