We came here on a very expensive day tour from La Fortuna since we didn't have a rental car, and my wife and I both thought the cost was worth it! What a beautiful place and an enjoyable hike!
Two responses to other reviews:
1. True, you cannot swim in the river/waterfall, but we did not see any police bossing people around, nor was it particularly crowded.
2. The hike is not that hard if you are in remotely decent shape - the people who are complaining that the hike was too strenuous must never get off the couch.