Máncora is worth a visit although it's a bit of a hike to get there. Whether you fly to Piura or Tumbés, you've got a two hour trip overland to get to Máncora itself.
Be cautious there: muggings and robberies are pretty common, and recently there have been reports that some of the upscale hotels along the beach road to the south of town have been hit by robbers arriving and departing by boat.
Security is better at the Punta Sal resort, about an hour north of Máncora along the Panamericana.