It is a good option for mountain bikers, hikers or trail runners who want to go on a quick day outing or for those without a car. Except for one thing: it is incredibly difficult to find the trailheads!
The park has a nice network of GR trails, marked by red/white or yellow/white paintings. I have to admit that, after two years worth of attempts, I have not yet found the ideal way to get to the strictly wooded areas from Barcelona. This trailhead goes straight into it, but if you're on foot, you will have to take the FGC from Plaça Catalunya to La Floresta and still hike a little ways.