There's a lot of different ways to take notes nowadays, typing, iPad/tablet, or old fashion paper. Honestly, old fashion paper and pen is the way that I like. The major downfall is that I have notes all over the place and then sometimes I leave my one notebook at home or at the office, etc. I'm mostly electronic with all my workpapers, but notes as I mentioned I prefer to take pen and paper.
The other major downfall with notebooks is that once you start to accumulate them it can be hard to go back and reference a single client's item if you're not 100% sure what notebook something is in.
I look forward to other's opinion!