You'll find great trails, beautiful views of the valley, caves, and the infamous Janela do Céu (Window to Heaven waterfall). Worth a day trip, at the very least.
The weather can change drastically in the mountains - so check the forecast before you go!
This national park is nice but has are few severe problems. In order to get there one need to drive 25 km of terrible dirt mountain road, which take 1.5h at least not counting the rest of the way. There is no information point at the entrance of the park. One have to go more than 1km to information center...
We stayed for three days at the park. Every day we went for trekking in good trails, with plenty of signs telling you were you have to go, how long and what you will find. There several waterfalls, beautiful views of the valley and if you like bird wacthing is also something to do. Loved the experience.