Casa da Ermida, managed by the wonderful Joao and Isabel is a place to go to get away from it all. The only room I would recommend staying in would be the suite which is incredble. The rest of the rooms (which we looked at) I don't believe could be considered good value. Spend the time kayaking or swimming in the fresh water lake or walking in the surrounds. Recommend that you buy some basic picnic supplies in Campo Maior or in Badajoz / Elvas rather than pay the 35 EURO for a picnic lunch. Joao and Isabel speak Spanish and Portuguese but limited English. If you want to book (which I strongly recommend) best is to book via secretplaces.com as the owner also doesn't speak English and if booking direct requires prepayment via bank transfer - no credit cards accepted!
Our stay (to celebrate a birthday) was just what we needed - lying on the bed in the suite looking out of the floor to ceiling windows over the lake I felt that I was in Africa overlooking a wonderful vista. It is 2.5 hours drive from Lisbon but absolutely well worth it. We will be going back.More