Definitely worth a day trip or more. Take the tour...

Definitely worth a day trip or more. Take the tour bus at the beginning so you can map your own path through. The hippo exhibit was particularly impressive to be so close to such a frightening animal.
The cats here are also great to see although don't be mad if they sleep the whole time you're watching. The mixed animal exhibits like all the monkeys and apes were fun to watch and the sounds were great. One of my favourite little things was watching exhibit animals mixing with random wild life from the area. Like ducks. Ducks all up in the flamingo exhibit.
Come on a cool day in spring and you'll see a lot of movement and babies.
If you're in San Diego, this is a must see.