Ipad is big, or better yet larger than PDA or Itouch. I guess you need to decide what you are going to use it for? I use the Ipod Touch, has all the applications I want, small, light, and does what I need it to do. Basically, I use it to replace carrying all those books and the quick search functions. Can a PDA do the same? sure, so can the Ipad. For me it came down to size, cost and convenience.
Research the app's first, then what your expectations are, I think with those two items you can make a educated decision.
BTW, in my class of about 70, maybe 5 of us have electronics, my school while wireless, the nursing classes have barely any signal and some clinical locations get edgy when you bring out the hand-held electronics. Just food for thought.