I recently acquired one thinking it was going to be a cool and useful feature, and the only time I think to use it is when I brush away a loose cat hair and my cursor goes all over the place. And the tablet mode, I think I used it once as a novelty.
Sometimes, mostly for a quick volume or pause/play press.
Being able to fold it right round can be useful as it uses less space when you are just playing a video or something. (Less chance of damaging it while cooking too!)
I got a fancy one with a pen, but found that trains are really not as smooth as I thought so the plan of learning to draw on the train never happened.
Edit: the pen support has come in useful for electronically signing things multiple times!