I've already heard the DRM is VERY tight.
Don't care much about the DRM as long as they offer a wifi approach to loading "personal" documents aka "public domain" or non-DRM. It would be a bummer if they claim "epub" but then it turns out they use a proprietary DRM for epub so there is no choice of where one can buy one's commercial epub books. Nook for example has a great wifi but you can't use it to load your personal documents onto the Nook -- you have to USB them. USB gets tiresome once you hook up your ebook reader for literally the 1000+ time. I am suspicious, as you suggest, that iPad will also have this restriction -- in that they already showed that one has to use USB to sync to your other Apple devices. Hopefully there can be or will be a third party competitor for the iBooks app.