I saw this dubbed in other language and have the same opinion as most users here. My conclusion is that if you want to focus on realism, you'll have to give up on character's emotions and expressions. Simply because "real" lions and other animals don't have such expressions. Raise your hand if you ever saw a lion smiling or crying.

The result is that you hear a certain emotion, but you don't see them. We immediately think the cast was awful because there is no association between sound with image. But it's actually a visual problem.

Music is awful as well. Very bad film. CGI was great but it's just unnecessary and makes things way worse on this case. I hated it.