As of now you can actually read books on the iLiad, and not on the Astak.
So, if you
need it
now, it's definitely a no-brainer.
If don't need it now, and you can wait, probably you don't
need it at all.
So you can wait for the Mentor, then you can wait for the new kindle, then for the Apple, then for the new Sony, then for the new Cybook, then for the new iLiad..................
When you
need it, buy the less expensive or the one that fit you best and you'll be happy.
If you just
want it, go for the two of them and you won't miss them....