Newsstand isn't iBooks for magazines or newspapers, but it is a centralized place to put all the magazine and newspaper apps for your iPhone and iPad, and a quick way to get to the Newsstand optimized section of the App Store. A few publishers have said that alone has substantially increased their revenue, but what has it done for us users?
It lets us more nicely organize those newspaper and magazine apps, and we get to see front page or cover art rather than the app icon, but the apps themselves are still a crapshoot when it comes to quality and design. iBooks are pretty unified -- I buy a book and I know how to navigate through it and easily read it, and I know if I put it down on my iPad when I leave home, I can open it up and keep going from the same place when I open it again on my iPhone at work. If I want to read my Trashy Gossip Mag, no such luck.