I've lived near some very impressive, large-city zoos for most of my life. So, my basis for comparison is the National Zoo in Washington, DC, the San Francisco Zoo, the Oakland Zoo and San Diego Zoo.
I've been here 4 times in the last 8 months that I've lived in Hamilton. I have small kids, so it's not a big stretch to take them to a zoo. That said, I really love this zoo. It's much larger than I would have imagined for a city the size of Hamilton. It also has a wider variety of animals that I would have expected (including many of the large, traditional zoo animals like rhinos, giraffes, zebras, tigers, cheetahs, many primates).
I like the layout of the zoo, which is spacious and includes a lot of natural things in the animal exhibits (that is to say, it's not a bunch of concrete enclosures). Much of the walkways are nicely shaded. There are plenty of benches and picnic tables that are nicely spaced out (especially for the little ones). There is a playground near the entrance, so the kids can run around and get a little more energy out before you leave.
I'm not overly impressed with the cafe - it's fairly standard fare in terms of coffees and cold drinks. I've had lunch here twice and, despite having low expectations of "zoo food," I was still disappointed. For example, the burger was just awful. But, as long as you're not coming here for the food, you should have a great day. Plus, you can bring your own food/drinks and make a nice day of the visit. There is a little gift shop if you want to grab a souvenir before you leave. read more