I really like Peak for what it is.
The exhibits are large, well planted, and the signage is really good.
I like the fact that at the Wallaby talk, you can feed the wallabies, I like that four species of Lemur are in the walk through. They have a great Tapir and Penguin exhibit too.
Maneless Zebra's are cool and the marsh for Sika Deer is very pleasing.
There is no real main exotics and it's rather basic, but the Pizza cafe is great, the talks are informative and for me, visually they have some of the best exhibits in the UK, and only the Otter exhibit is poor.
I do like the Squirrel walk-through although I've never seen a Squirrel there! They probably have the friendliest Dik-Dik as well.
I disagree about not being able to spend a day there. If you like photography and listening to talks, and seeing the animals up close in great exhibits in picturesque settings, then I think that Peak is a lovely day out
The only thing I've criticised is they could do much more there and it's a shame they don't hold many animals you wouldn't find at a small zoo / farm park, especially when it's sister park Manor House, houses Gibbons, Rhinos, Tigers, Red Panda's etc, and again has the same amazing exhibits.
I love both parks for what they are, prefer Manor because of the species, but I always enjoy a day at both.