The drive up the hill is grand. The dam is magnificent and the scenery is fabulous. Entrance to the park will set you back just 1 trl per person (~€0.33).
What stuck me the most is the total lack of development of this 'attraction'. There are a couple of run down restaurants here and there. The entrance resembles your avarage...
Took some photos, looked at the water, etc.
I passed the time lecturing my wife about hydro-electricity production and the difference between amps, volts and watts, but she looked bored. Not sure if it was the dam's fault or mine.