We visited Nandankanan National Park in August. It is a nice & well maintained national park with very informative details about the zoo & the animals.
The entrance itself gives you a brief about the park with its huge map mentioning details of complete national park.
It is best suited for families with kids, but please keep in mind there is a lot of walking if one want to cover the whole park which may make you tired.So prepare yourself for a nice walk locating animals. For food part, you can find lot many eateries outside the park.