I agree that the page turn bar on the left of the device is not that useful.
I think I'm the only one that uses that bar all the time. My main reading position is to hold it in my right hand with my thumb on the right, first two fingers wrapped around the top, the ring finger at the corner, and pinkie on the left-hand bar. I use the pinkie to push down or pull up (the ridges help a lot on the pull up) and turn pages. IIRC none of the other readers would let me have the ability to turn pages while holding it from the top.