Personally I would only buy one if it is not going to be portable as the bigger the screen, the easier it is too break.
I would wait for the first of the plastic substrate screens to come out, hmm Plastic Logic ?
PVI (E-Ink) have recently demoed some large plastic screen devices but estimate that they may not be in the hands of customers till Q1 next year.
I would like a wifi based A4 sized reader combined with touch and stylus