Everyone has their opinions, and I'm certainly happy to offer mine.
. I'm finishing my last two pre-reqs in the fall, and I primarily use my iPad. I take notes in Evernote-- you can type them in OR use Evernote penultimate if you do better writing by hand. In evernote's suite of apps, I am able to add diagrams from my book, pictures, video, and even the recording of my lectures. For me, it has been extremely handy and helpful. I've used my iPad for projects, to collaborate with other group members, and this morning, I used it to rough out a landscape design for my side yard. (Eeeeee!!! Fun stuff when school is out but I'm still busy as a bee preparing for teas and CNA exam!!)
Personally, I have a laptop at home, and for writing papers and for some of the things my iPad just doesn't do (flash), the laptop wins. However, really, I use my iPad more than anything else. I always have it with me, and always have access to my notes, the Internet, etc. it's handy. If you have a laptop that functions for writing papers, and it doesn't need to be replaced just yet... A tablet might be helpful. But remember, you can't use them for absolutely everything, and you may want to check with your instructors to see if they'll allow you to use it in class. Otherwise, you might wind up buying something you can't even use.