They had two advertising messages. There were the 'Really?!' ads that were promoting glance-and-go but there were also the Xbox avatar ads that were promoting full fledged immersion in the service. Microsoft offers both experiences: the basic system itself is all about being light and providing a important information quickly and if you gets their apps you can spend as much time as you want in those. Contrast with iOS which is all about the apps and Android which errs towards an overload of information in the limited space.
I think glance-and-go is the future really. Most people have a smartphone and desktop/laptop now, so they spend a lot of time with the phone, but as tablets get more uptake we'll see smartphone use plummet. Most people will spend their time with the tablet and won't want to dig around the phone just to read messages or listen to voicemail.
I don't think Microsoft has gone far enough in the glance-and-go direction. The system still needs another form of alert so I don't have to turn on the screen to check notifications. The tiles feature, as brilliant as it is, still can't keep up with all the alerts that a true notification center might be able to handle. If those features were included in Windows Phone it'd be my go to device right now. As it is, I've abandoned phones and switched to tablets entirely.