When I was in high school and didn't do much writing on keyboard, I couldn't get used to how writing on keyboard felt so foreign and hindered my thought process. After I got used to writing on keyboard, doing it in handwriting felt foreign in turn.
Presently, as I rely more heavily on my computer, I've gotten more comfortable with expressing my thoughts through the keyboard. It takes a while to get comfortable when switching between the two modes. And that interferes with creativity for a while. I love the opportunity to edit on a computer, writing things by hand, then correcting all of it and rewriting is so frustrating. But once I get comfortable with it, there is no noticeable difference in creativity. It all depends. I write best when I'm in a very good mood despite the mode of writing.