I visited the Serengetipark Hodenhagen last weekend for the first time. Reading back into this thread, I can see it has generated some controversy of the last years. While I honestly had a lot of mixed feelings while visiting, I left with quite a positive view.
From a zoo perspective, the main attraction in Hodenhagen is the so-called Serengeti Safari, which, despite the name, features animals from all over the world. It includes many of their big ticket species like elephants, rhinos, tigers, lions, cheetahs, leopards, baboons, green monkeys, giraffes and most of the remaining hoofstock. The large drive-through paddocks are honestly very good, though some of the side exhibits with primates are not (more about those later). Highlight was obviously a very active group of rhinos. Because their paddock is so large I actually saw them chase each other over decent distances, something I have not witnessed in any other zoo or safari park. It was also great to see large herds of hoofstock, including blackbuck, dybowski sika (new for me!), kulan, wapiti and scimitar-horned oryx.
The park also hosts another safari, the Jungle Safari, which one experiences on foot. It showcases mostly primates (I saw chimpanzee, mandrill, white-headed marmoset, black-and-white and red ruffed lemurs, ring-tailed lemur, and siamang. Capuchins, squirrel monkeys, cotton-top tamarins and white-faced saki were signed but unseen), along with a couple of odds and ends (domestic sheep, prairie dogs, meerkats, red-necked wallaby). In theory it is split up in different geographic areas but at the moment of my visit it was a bit of a mess, partly because it seems several species have been shifted around, and partly because of construction work. All of the walk-through enclosures were closed during my stay because of covid-regulations.
The quality of the primate enclosures is very mixed, ranging from very good to barely acceptable. With the exceptions of some of the lemurs and the walk-through enclosures, all of the primates live on islands, and many of them are smallish, and some have a decisive lack of structure. With only a few climbing frames and ropes, the exhibits for siamangs and spider monkeys do not offer the physical and mental simulation these arboreal primates need. The large (new?) ring-tailed lemur exhibit and the capuchin island with plenty of real and climbable trees are positive exceptions. In general, the more terrestrial primates (baboons, mandrils) do better here. The only great apes in the zoo are chimpanzees, and they also live on an island. From a distance I already though that their enclosure was not particularly large, and upon closer inspection half of it was actually occupied by the mandrils. From a visitor perspective it provides great views, but I'm not sure this enclosure is ready for the future. The mandril exhibit is better than most I have seen, but the bar is quite low to be honest. None of the primate enclosures are actually bad, but most of them aren't very good either. The stark contrast between the smallish primate islands and the huge areas for hoofstock doesn't help to temper criticism.
The final animal attraction is the "petting safari" which is basically a large walk-through paddock with goats, sheep and alpacas. It is quite nicely done, to be honest, but not really exciting. Perhaps also important to note: the park is extremely mammal-focussed. The only non-mammals I saw were flamingos, greater rhea (both white and grey), ostrich and grey-crowned crane. Chickens were signed but unseen.
The Serengeti park is expensive (over 40 euros for an adult!), but also has a huge amusement park area in the back of the park. While I'm personally not fond of this combination of amusement park and zoo, in this case both can reasonably stand on their own, even if the ticket price is expensive if you only visit one of the two. The park has also an enormous amount of overnight lodges, and people who stay there can visit the park, including some animal exhibits and a huge amount of playgrounds, until dusk. See the Serengeti Park as a zoo/safari park with additions, and it comes across a extremely commercialized and expensive. But if you see it as a high-amusement family friendly resort, everything falls into place. And given that a long row of cars was waiting for the park to open, even at the very start of the season, it seems that many people see this more positive aspect.