Drexel University has a similar program requiring five years to complete. However the co-op's are for six months at a time which is infinitely more useful to both the student and employer then more frequent shorter co-op's.
I became good friends with the Waterloo student working in our department. The interns throughout the company (a few other Waterloo students, some other schools too) would hang out together at lunch every day. Another Waterloo student rotated in while we were there as well. The four of us from my school lived in an apartment in the same complex as the Waterloo student, who had three Waterloo roommates working at different companies. We got together for quite a few activities and dinners outside of work and got to hear stories from their friends about the other companies they were working at.
I agree that six months is a lot better to really get involved in the work and accomplish something, but the short duration internships certainly kept them on their toes. Also, as stated elsewhere in this thread, they do have the ability to double up their time at one of their positions. I was pretty envious of the huge amount of connections they have and the fast, relentless pace of their program, but not so much of the fact that they have no breaks!
Compare that to some places that do an entire 16 month co-op at once in the middle of your program (e.g. McMaster). I've heard horror stories of people knowing in the first 3 weeks that they were going to hate working there, but were basically obligated to work there for another 15 months to get credit. You can put up with almost anything for 4 months.
That, and it's much easier to schedule classes to be shared by non-coop students and coop students when the terms align (non-coop do 8 months school, 4 months summer, etc).
Edit: fail math x2