As a performer for a big screen, Rosanna Roces manifested her talent for acting even in her early films. In Celso Ad. Castillo's Comfort Women (where she was still billed as Anna Maceda), she easily stood out from the rest of the all-female cast despite the fact that she was clearly playing a supporting part.
Even in the exploitative film Basa sa Dagat, Rosanna managed to rise above the hopelessly sordid material by giving a very decent and respectable performance. Quite a feat, I have to say, especially since she's half naked during most of the screen's running time.