In my opinion its one of those tourist traps that are worth stopping for a look...before moving on. Here's a picture of the rock as you descend into the town of Perce. The rock is truly spectacular from the beach, nearly 1/4 mile in length, and visible with light binoculars from Forillon 40 km away. The town, however, looks like Martha's Vineyard at the height of summer, complete with packed sidewalks, ice cream, and unending shops full of all the same souvenirs. We pushed on to New Brunswick before stopping for the night.
Unique Suggestions: Why not get some poutine?
You can walk out to the 88m high rock, if you would rather not take a $40 boat tour, and can brave the cold water. When the tide is out the way out is dry, but these folks were a little late! Nearby is a large island (Ile Bonaventure) with an incredible number of sea birds including the striking Gannet, so you can take boat tours that combine both(~$80), and leave you time to wander the island trails. A bit pricey though!
Although you cant see it from the beach, the rock has a natural arch. Hence the name: Rocher Perce (Pierced Rock).