Kap Kig Iwan is one of the smaller provincial parks in Ontario, but it packs a lot into its foot-print. There are all kinds of trails, including some disused roads that lead around parts of the park that may or may not be "closed off" at the time (depending on whether Ontario Parks wants people to be camping there, which seems to change from one year to the other), and some amazing look-outs, but by far the biggest attraction is the impressive set of rapids and waterfalls. The park is set in some pretty hilly country in the Canadian Shield, which offers gorgeous views in all seasons of the flora, and of the Englehart River winding and crashing through the park. As I said, it's gorgeous in all seasons, bright green in spring and summer, golden in the fall, and snow-covered in winter (the falls also get crusted in naturally-formed ice sculptures in cold months). A big bonus, as the advertise in the Ontario Parks guide, is that there are very few bugs even in late spring. There's very little standing water, so there aren't many spots for mosquitoes or black flies to breed.
Spend some time there poking around and you'll find all kinds of trails that aren't marked or often used. Some of them are little jaunts into interesting nooks of the park, while others will take you to huge, gorgeous features like enormous sand escarpments, hidden look-outs, and a calm, broad stretch of the river with a flat stone bottom and glassy water.
Kap is a superlative little park, especially if you take some time to poke around, and there's something to be enjoyed any time of year.
It's enjoyable for people of all ages, but keep an eye out for little ones as there are some dangerous spots (especially around the rapids). There is vehicle access that gets you close to some of the major sights, in case mobility is an issue for you, but there's not much by way of wheelchair access. The park is seldom, if ever, busy, and I've often been there with the only group of people in the whole park.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.