As this article points out, the upcoming Ubuntu installer using the slide show approach is really not all that new of a concept. More professional, sure. But Simply Mepis, openSuSE, Linspire, Mandriva among a number of distros have been offering this type of thing for as long as I can remember.
The idea is a simple one. Provide relevant content about the operating system being installed while the end user is actually going through the motions of waiting for the install to complete.
As to why it took Ubuntu this long to get a handle on it is anyone’s guess. I suppose it was not seen with immediate importance, which I can surely understand. Will it help to provide new users with a sense of what the operating system is capable of? Potentially, sure. But it depends on what content is provided during the slide show install itself.