I am a note taker on the whole, but don't really take notes from the books I am reading for entertainment. However if I get a new text book that's a different story, I read it with pen in my hand, then I underline, circle, tick, star, etc. Then I take notes. It also helps when I am looking something up , even years later, certain facts will jump out at me.
That's one reason I want something like the Amazon Kindle because you can highlight without possibly ruining the book.