I was at this zoo last year, only zoo in Europe I've been to.
It is not only a zoo, but also an amusement park with rides, a swimming pool, haunted house etc. However, there are no animal exhibits in this area except for a parrot cage, so if you don't want to see all that you can skip it.
As for the orangutans, when I was there there was only 1 out. I don't know if there was another hiding or off exhibit. The exhibit is shared by a pair of Lar Gibbons, with a tiger exhibit nearby which I believe was opened recently. Strangely, there was only ever 1 gibbon out, and the only way I knew there were 2 was because I heard 2 gibbons calling.
There is a tropical house here too. The main room has exhibits for most of the primates: Golden Lion, Emperor and Cotton-top Tamarins, Chimpanzees, and Ring-tailed Lemurs. There is a small side-room which houses the squirrel monkeys. The chimps and squirrel monkeys have access to outdoor exhibits, and I think the lemurs do as well but I don't remember. There were no walk-through primate exhibits though.
Also in the main room are some finches, and after passing this you enter the main bird room. This zoo has a tiny bird collection. Just a few Goldie's Lorikeets, a SouthernCcrowned Pigeon, a family of Crested Partridges, Superb Starlings, 2 or 3 Laughing Kookaburras and a toucan. All the birds here are free-flying. There's also another enclosure in here for Cotton-top Tamarins with twins. The tamarins and birds also have access to separate outdoor areas, like the larger primates in the main room.
There is a side-room in the bird house as well, and this one is the indoor quarters for Greater Flamingos though they were always outside when I was there.
The last room in the tropical house is home to reptiles, fish, etc. I don't remember any of the species in here.
Around the tropical house are some more exhibits. An outdoor exhibit for Black Spider Monkeys, another for macaws, as well as the outdoor Flamingo exhibit. They also have Black-and-white Ruffed Lemurs here, and while I must've been right in front of the cage, they didn't show themselves. They were certainly there though, if you've heard ruffed lemurs in a zoo before you can't mistake them for anything else. I think they used to be inside the tropical house and were recently moved to an outdoor exhibit. There are also free-ranging peafowl which hang around this area.
The area with native wildlife contains wolves, moose, owls, capercaillie, otters and a few others. The exhibits are seen from a boardwalk and are usually very large. I think they had lynx too. This is also a much quieter area than the rest of the zoo and only some people go to it.
The last area is the African section. The lion exhibit is the first thing people see when they enter the zoo. The zoo has either 7 or 9 lions, can't remember how many now including cubs and 2 males. The enclosure is surrounded by a mote and is large. This area used to be a pool for 2 seals but this is gone and I have no clue where the seals went.
There are also exhibits for various hoofstock and meerkats in this section. These have been here for a few years but aren't bad. Don't remember what species though...probably common ones. I know there weren't any unusual species.
For what it is it's a good zoo but the price is expensive for what it has to offer if you're only going to see the animals.
Hope that helps, as there isn't much information on the internet about this zoo...