The park offers a fun day for people of all ages, or at least those not scared of rollercoasters, heights and speed. The rides are mostly all fun and have lots of "replay value." The biggest problem here is the amount of people taht come to the park, especially on weekends. To avoid huge lineups and problems with parking, try to show up as soon as the park opens at 10am or in the evening a few hours before closing. Midday is the busiest time. If you're in town for a few days, try to visit Wonderland during a weekday when it is least busy.
There aren't many healthy food choices, almost none in fact, but most people don't go to amusement parks to eat salad and organic quinoa. They do not allow you to bring food or drinks into the park either.
The whole experience is pricey with admission at $34. If you are willing to dish out the extra cash or don't have the whole day to spend at the park, the Fast Lane passes allow you to skip some of the massive lineups (~200+ people for popular rides). They start at $50 a pass. Expect to spend most of your day waiting in line for the rides.
Check out redTag.ca for occassional deals and buying tickets on Wonderland's website can also score you some discounts and save time.