I just posted a big FAQ about the $30 data plan here:
Some campuses have good WiFi, but it depends on how often you're off campus. If you commute a lot by train or bus to your hometown (like every weekend), the data plan can relieve some Greyhound boredom, and allow you to get some work done, that might require Internet use. The Northeast Corridor, is like one big massive WiFi hotspot -- reception all the way from Niagara Falls-Waterloo-Toronto-Ottawa-Montreal-Quebec City. (Although other parts of Canada is clearly lacking: not much Reception in Newfoundland)
I don't recommend getting the 6gig/$30 if you're a starving student, though.
Hopefully the FAQ answers questions about whether or not it might be worth it;