With Moose, you get the road-trip experience without having to worry about driving the car or finding directions and places of interest. You'll still stop at interesting sights along the way, and you can spend several days in spots that really grab your attention. A lot of what you're going to want to see on these routes is already built in to the trip itinerary so it's a lot easier than making your own trip via Greyhound buses, but you do give up the one Greyhound perk: frequency.
The full Western network includes Vancouver Island, Whistler, the Okanagan, Banff, and Jasper ($1059 for a minimum of 15 days, R/T Vancouver), and you can pick as short a trip as 2 days to Whistler ($80). Some meals are included, as are taxes, fuel surcharges, a tour guide driver, and sometimes small activities and park fees. Accommodations are not included, but a hostel dormitory bed is guaranteed at each overnight stop ($20-38/nt).
Eastern tours range from a Niagara Falls day trip from Toronto ($55) to the full journey out to Nova Scotia ($1439 for at least 20 days R/T Toronto), and even forays into the US (US tours sold out for 2011). Accommodation is pre-booked for each passenger but is an additional cost.
Tours don't all depart every day so check the schedule for the next bus before you decide to hop-off and spend extra time somewhere. Discounts are available with various backpacker, hostel, and student cards.
One blogger happens to be riding the bus right now... follow @ibackpackcanada on Twitter or watch for posts on his blog to get his take on the experience.