Answer :

Positive: You get to see different animals, see all kinds of habitats, learn new facts about all the animals and see them maybe in action! 

Negative: They might be sleeping, In a cage or fence so they can't get out, restricted. 
In my opinion, the only advantage is that endangered species will be given thechance to reproduce and their numbers will increase. Apart from that, I disagreewith any animals being caged or kept in even a very large fenced area. However,it doesn't take a genius to realise that there are people (poachers) out therethat will do anything to kill off these precious animals for money, endangered or not.