Sadly, iBooks is not Apple's finest hour.
To be sure, I don't think Steve Jobs' heart was really in it ("Who reads books?"). The app is ridiculously slow. The interface is poorly laid out. It doesn't always remember my place in books, either between devices or even on one device. The cloud integration is hopelessly confusing. Ebook prices are much too high, when you consider that you can't lend or give books to someone else.
It's just another app from Apple that feels worryingly abandoned, like the music app and their iCloud services generally. My conclusion is that real books and CDs are still a significant market, because Tim Cook has said that his philosophy is to "follow the money." That suggests that there is not so much money in ebooks or digital music, so therefore he's not concerned with focusing on making their apps good.
That is directly opposed to Steve Jobs, who loved music, and therefore wanted to make sure the whole experience was excellent. He achieved that in hardware, software and services—the iPod, iPhone, the iPod app and iTunes. All three of these are being degraded by Cook; hence the too low storage on the iPhone, the awful music app and the neglect of iTunes.
Cook is a money man; he ruthlessly follows the money and that's his driving force. Steve's passion was music. His driving force was to build an exceptional product and experience for music; the money followed as a result. This reveals how Jobs led the way through his passion, whilst Cook is led the way by money. It's a subtle difference; I would say that Steve was an active leader, whilst Tim is a passive one. Steve led by investing in something he really believed in. Tim doesn't know what to invest in, so he agrees to lots of different things, but is only led by the bottom line.
