We visited on a chilly fall day in November and the crowd was pretty light. The cost of admission goes down during their winter hours so it was only $8.25 for adults. Parking is free. Due to the colder temperatures some of the animals were not out and only a couple of places to eat were open. We ate at Pizza Hut and took our food inside a building right next to the stand so we didn't have to eat outside.
We particularly liked the aquatics and primates; we took the tram to see these exhibits. Everything was clean and well taken care of and the animals looked healthy. If you don't like crowds then the cooler months might be a better time to visit albeit not everything is open and running.
Don't miss the opportunity to visit the rainforest building which is included in the cost of your admission. They have more animals and exhibits in here along with a restaurant and restrooms. I'd definitely recommend a visit. There are lots of places to sit and rest if you get tired from walking and there is enough to see that you won't get bored.