Tons of restaurants (too many, almost). At least 2 fairly big clubs.
Some Hotels/Restaurants with Bars/Bar Seating:
Brisas Del Mar
Casa Zen (beer/wine only)
Almost all the bar seating in the restaurants is small, 10 seats or so, and the vibe is going to be pretty mellow at them.
Clubs (they start late and go late, and are usually kind of a scene):
D&N (aka Tabu)
Whatever the former Howler Monkey is now (bit of a sports bar, or was), by the crossroads
Its not that there isn't nightlife -- its that everything is stretched out over 3-4km, and some places are tucked up or in 100 meters or so from a road or sidestreet.
Keep an eye out for flyers and ask people what's going on, over the years I've encountered fire shows (on the beach or otherwise), jugglers / street performers / drummers / dancers doing shows in at some of the hotels/restaurants, etc. Mostly during high season, though. If your friend visited at low season that would account for his impression.