I wasn't really sure which one to get either. From my reading I gather the cybook is the best (and value for money) if you just want to read. The iliad lets you take notes etc. which I wouldn't use anyway.
I've started a wishlist at books on board (an American site) and I'll mainly order from there - seems to be good prices and a huge variety. Some of the books I found on books on board aren't available at Dymocks yet and there was a fair price difference. (It also shows the price in AU$ which is handy for us.
Hope I've made the right decision I'm still waiting for it.