I find 70% or more of the books I search for aren't on there..I want to keep all my digital books with one vendor for ease of use..
Just buy ebooks from Amazon (or where ever), remove the drm (just google this to see how), and then load into the iTunes library.
Calibre converts to pub for free.
I'm annoyed that on amazon the magazine subscriptions are "exclusive to the kindle device"... I wanted to subscribe to Time Magazine the other day and got this message. With the trouble the magazine industry is in, it's just dumb for them to have signed THAT deal.
Time Magazine has an iPad App. But they sell issue by issue