Mizzy Lake Trail is a 10.8km intermediate loop. Parking is directly on the trailhead and this trail is walked regularly by many park visitors. If an emergency happens on the trail you could expect a reasonable response time since it is an official winter trail with an accessible parking lot. I think the average person can complete this trail in 5 hours. If you're experienced it is possible to complete in 4 hours or less. If you're less experienced perhaps give yourself 6 hours.
Why am I rating such a 10.8km trail as intermediate? It's because Mizzy Lake Trail doesn't ascend any significant elevation. This trail predominantly visits wetlands so it is remarkably flat and easy to hike (at the 3/4 mark there is a brief hill). Mizzy Lake is a bit like Spruce Bog, but 5 times the length. In fact, the only daunting thing about Mizzy is its 10.8km length. The trick to enjoying this trail is to give yourself lots of time. An ideal start time would be 10am. If you walk at a comfortable pace you will love this trail.
Everyone always asks about wildlife. Yes, this is THE "wildlife" trail, but don't forget, wildlife is never guaranteed. The wetlands and ponds that Mizzy Lake Trail visits are ideal habitat for Algonquin animals. This doesn't mean that animals sit on the trails and pose for photographers. Wouldn't it be great if it were that easy? It really comes down to luck, timing, and how quiet you are. If you don't see any animals, that just means you'll have to come back again!
Although this trail does not have a scenic lookout from a cliff, Mizzy Lake affords you with excellent views of wetlands and ponds. Although you don't get the breathtaking view, Mizzy Lake gives you a more "intimate" peek into Algonquin Park, getting you closer to the ecosystem that breeds the most life: the classic Canadian wetland. The birding at Mizzy Lake is very good year-round. Large mammals (moose, bears, wolves) do appear on the trail, though again, it comes down to luck.