I guess it depends on your course. When I did Computer Science, I don't think I purchased one single notebook. Going into Medicine this year and the idea is to make digital notes on the iPad, make notes directly onto PowerPoint presentations, and I guess take images and annotate any handouts. Although I am considering notebooks because I love writing, but the inconvenience in storing paper notes may avert me.
Maybe some courses like English might have you doing a lot of writing in class, but in terms of lecture notes there should be no problem with going digital. My plan is to carry an a5 notebook with me if I need to make any sporadic notes, and then you can always create them digitally when revising later at home.