I cannot get my wife to try ereading for all the reasons attributed to children in this thread. It is a leap to go from the tactile sensory process of reading a book to reading on an ereader.
IMO pbooks are better for young children because they are experiencing the entire process of reading from pictures to the cover art to the fancy fonts at the beginning of each chapter. If they transition to novel reading that will be less important. Who does not have fond memories of the children's books they had access too down to the littlest detail.
My 13 year daughter who is the real reader amongst my children just inherited my Nook 1 and has not put it down, I may try again with my wife on the NST since it is less techy and more intuitive to read on.
I say expose your kids to reading in any and all forms