If you want to swim, the beach is wide, clean, and generally safe, but the water is cold (as in all the western coast) and most people prefer to learn or practice surf.
July-August have the usual problems of crowds, but in all the other months the beach is a space of freedom and health.
Nazaré is (fairly) the top destination among the western beaches of Portugal. However, for those who prefer more quiet and isolated beaches, there's a second line of much quality: Baleal is one of them, and the camping park and the few apartments that line the beach, only in peak months add a significant movement to it.
Ten months a year, it is a refreshing "out of the beaten path" for the Portuguese (and other).
No, I'm not a specialist - as a matter of fact, I never tried surfing. But the enthusiasts that I know, they all merge here, in all their free time. Maybe because the surf is good, maybe because there's a school in place with cheap surfboards' renting and wet suits, maybe because it is not crowded, maybe because parking is easy out of peak days, maybe because it is beautiful, maybe because...yes!
In a free day, Tito came expressly from Lisbon, and I spent two relaxing hours watching him and friends "bathing" the surfboards.