@snowleopard I loathe to say it, but it is clear that much more effort was put into some of the landscaping and architecture at Mondo Verde than into some of the exhibits.
As far as highlights go... personally I like this place far less than GaiaZoo in the nearby Kerkrade and I have mixed feelings about this place and some of its exhibits. However, I did enjoy the Tropical hall (although it did have some questionable exhibits in it) and the large aviary a lot. Some of the gardens were also admittedly quite nice to see.
Also, if you are in this region, I would advise you not to eat at this place. Yes, the entrance price is including all you can eat food, but the food is very low quality.