I've had my ereader for over a year now, and I still really like to use both formats.
I get paper books from the library quite frequently, since that's free and has a lot of stuff that is unavailable as an ebook, and it's also fun to just browse the shelves; I buy second-hand paper books when I find a particularly good deal on something I want to read; and I buy new signed hardcovers (if I can find them) of my absolute favorite books after having finished them - usually no more than a couple times a year.