I'm amazed. I thought DiGi stated RM30/month but it's RM25/month.

It is stable, not to worry. It is not that fast but stable and most of us are satisfied.
Only for around RM 25/month, it is affordable. I have used for around one year of Celcom D98 (RM 98/month), was quite OK but became inconsistent and with petty 5GB fair usage policy. It really makes everything near to impossible. Anyway, DiGi EDGE has no fair user policy.
Make sure you can register for D' Campus package.

If your area is within EDGE coverage, then you will get EDGE else it is GPRS. Nevertheless, most of the areas are with EDGE now, so not to worry.
I appreciate if you could read the first post for more information.
By the way, is your college is listed here? http://www.digi.com.my/whatshot/promotions/dc/outlet.jsp
If no, I'm sorry then you cannot apply but if you have friend studying in any of these selected universities/colleges then you can use his/her ID card to apply.
It will end once you graduate. What will come after your graduation? Perhaps it will revert back to RM 66/month? I'm not sure.