I'm going to hold out and see how it goes. I'm not that sure, with the university being set out on a campus, I'll be needing it. The question you need to consider is: Will you spend more than £70 on bus travel this first term? I'm not sure I will.
Personally, I don't really mind walking around. Tesco isn't that far away, and I'll happily walk it (although maybe bus back with my bags!).
They are good passes, though. I had one while I was at college, and you could use any bus, any time, for free. But then I had to use a bus at least 4 times a day to get to and from college making it worth it.
The only time I see myself using the buses is to go to tesco, the odd shop and perhaps a night our or two (and I'm sure most people will stick to the uni events for the first so many week).
Not too sure, but NUS may give you say 10% off the fare anyway, I know our local service had something similar if you didn't buy a pass you could still get discount as a student.