Fun for kids, but be prepared for extra money
We went with our 5 yrs old daughter the day after Christmas, on a Friday. We arrived there around 5,20 and we found parking pretty easy, but cars were arriving at a rate of 10 / minute I would say.
First advice: BUY tickets online. That's how we did, and we just went through, while the lines at the ticket boots were already around 30 persons at that time.
Second advice: if with kids, try to take advantage of all the free rides there are for them. There are enough to keep you busy for the whole night, without spending extra cash on that. Be aware that, despite the advertise on the site, there are plenty of rides and activities for which you are expected to pay (which is really bothering, considering the price is big enough, and the fact that you still need to drink / eat something while you're there).
We did decide to spend money on the elephant ride, and we went all of us on the elephant, since it did seem like something fun and different to do. What I would recommend: try to go with some friends, and let them take a picture of all your family, as this will spear you the cost of them taking you the photo on the elephant. The ride is 5 $ / person, but the cost of a reasonable size photo is a whooping 20 $. That's why someone taking your pic while you are all on the elephant would come pretty handy.
Food and drinks are plenty, but you might consider bringing along at least the drinks, as you will find other stuff to spend your money on, if you really must.
I wouldn't bother trying to get in time for the shows. For example, the elephant show... there wasn't any! Despite the advertised hour for the begining of the show, they actually decided to rather take money from kids wishing to feed the elephant or families wishing to ride, instead of having the show. All shows seem old and you will find it hard to appear enthusiastic for the sake of your child. The magic show was a little more appealing to the kids.
All in all, it was a fun experience for our daughter, and that is what matters for a parent. But: come early, buy tickets online, bring alone some drinks (even a home made sandwhich for your kid - remember that food in such places is not the healthiest to give to your kids), and extra cash.