Many people are just looking for the N95-like gadget: all-in-one.
I was one of them until I encountered the Nokia 770.

That changed all. I like to have a phone to make calls and act as modem when needed and the tablet for everything else.

The key is the screen. To make calls you don't need a huge screen. But you probably want to carry your cellphone almost everywhere, almost always (Saturday nights with friends, for example).

But you do want a larger, crisp screen to surf the web, to guide you with clear directions and bla bla that you can carry in the backpack (that you might not want to carry when going out with friends).

You simply can't have both. Or if you do, you have to sacrifice something: screen for the N95, GSM with the tablet. And you can try to help in both cases (zooming and panning in the N95, VoIP calls on the tablet). Kudos to Nokia for providing both. Apple got it too: they're planning a new PDA. The real IT competitor.
We'll see.