I remember group projects from college physics. I hated it. As I recall, we had three decent students in my group and one slacker. The slacker couldn't even carry his weight by bringing in our papers. I don't think it was planned, but that is what happened.
In the "real world" of my library, we collaborate all the time, but it's usually a much more organic process instead of top-down assignments. Much healthier.
Collaboration in the workforce is what it is too. Most get paid the same (our reward) but not all work at the same pace. Often we find ourselves picking up the slack from a work colleague. Sometimes warranted but usually due to laziness from other workers. College is the same still. Some things don't change.