I will add my personal thoughts here as well...
Regarding holding the device... I have never found this to be an issue... I generally hold the reader with my fingers underneath the reader and my thumb generally resting lightly on the page turn buttons. Turning a page requires enough force that the weight of the unit doesn't turn the page on its own.
I agree that the page turn bar on the left of the device is not that useful. I wouldn't mind seeing it replaced with some sort of handle and page turn buttons on the next iteration of the product, but in general, I never think about it.
Right now, I consider the ergonomics of the device to be superior to the first generation Kindle, perhaps equal to the second generation Kindle (Though I have little experience with it)... and behind the Sony 505 (Not sure about the 300 yet). I actually think from an ergonomic perspective (other than the screen) that the ebookwise 1150 might still be the best over all unit since actual thought was put into the device about how it would be held.