My husband and I booked a half day private guided hike in September 2012. We had perfect weather, and the best hike of my life to date.. While it wasn't cheap, it was the highlight of our Canada holiday.
We are quite active, outdoors people, but also were a bit daunted by alpine hiking (being from Australia), so we wanted a guided hike. The best thing about a guided hike (other than the general confidence of having a knowledge guide with bear spray), was the ability to go off-trail. We hiked across meadows, up Quartz ridge (a real climb!), and were taken to places with stunning views. Once we left the main trail, we didn't see a single other person.
I wouldn't recommend Sunshine Meadows for people who don't have a reasonable level of fitness, but neither do you have to be an experienced hiker. If you get a guide, they will tailor the hike to your fitness and ability- our hike was perfect for us- made us feel challenged, but always safe and within our limits. We were rather exhausted when we got back to Banff!
If you don't want to pay for a guide, there appeared to be some well marked trails which allow people unfamiliar with the area to still do some decent half day hikes.
If you are going in September, make sure you take food with you- the cafe wasn't properly open and choices were limited.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.