Went to the zoo in February which is an off season. While food stands are not open, most of the exhibits were. The price is free, so you can't go wrong with that. Parking was $20, but that's OK since we didn't pay to get in. For a family of 5, that's perfect.
They are building a new elephant house which is supposed to be open late 2012 or early 2013 (I think). Perfect for viewing from what I understand from one of the volunteers. Of course there are the Panda's. Another must see. We spent the entire day there although in the winter some of the animal outdoor exhibits were closed, it was still a great day. My teenagers really enjoyed it as well as my youngest.
If you decide to eat the food there, keep in mind, it's a little pricey for your normal fastfood grill type fare. But it tasted OK. More places to eat during the busier seasons, but our family really enjoyed the lack of crowds. Worth the visit and we will go back sometime in the future.