Not the most exciting national park I've been to but I guess it's a nice place to visit if you have kids.
The entrance Fee (4,000 pesos per person - foreigners / 2,000 pesos per person- Chileans) is extortionate considering what the park actually offers (which isn't much).
The walks are very easy but some of the trails were very muddy at parts and should be maintained better.
The walk to the sand dunes isn't anything special either. The beach is okay I guess.
If it was free entry or at least half the price then I might bother coming here.