Well, there's no other alternative at the moment. The only thing students are bound by is the curriculum and recommended texts.
I for one, hope Amazon get onto it too. It's just a shame it's always Apple innovating and the rest left catching up. How and why did Amazon not see this as an opportunity years ago? They must sell thousands of text books each year and ship them everywhere.
Like Kodak, Amazon was making too much money off the analog format to seriously consider a move that would kill the current cash cow. Dabble in the digital alternative, yes, but ready for massive game changes from near-unexpected competition and overnight adoption by customers, not so much.