I got an iPad as an anniversary gift and have tried to use it for business. In the end, it won't eliminate the laptop - hardly - but it does have some uses.
Business/Professional Use
Good for reviewing documents on a plane where space is limited.
OK for quickly checking email. Instant-on vs. waiting for my laptop to boot up (though I'd argue my phone is equally as good if not better).
Nice/shiny wow factor for training - for some reason, people get a kick out of watching a video or reviewing slides on an iPad vs. on a screen/projector. In this way, I can see iPads replacing printed materials for training events or other presentations. Plus, anything electronic is easier/quicker to update vs. reprinting.
Entertainment
It literally does nothing that my Droid phone can't. The Droid even has a mini HDMI output, so I can stream Netflix to the TV of whatever hotel I happen to be in
My phone is also a mobile hotspot. With 4G, it's unbelievably fast, and compact.
I would add the keyboard case, but at that point the total package is the same thickness of a small laptop (and a small laptop is a few hundred bucks cheaper.
Conclusion:
Like anything Apple, it's nicely-designed, the interface is slick and all applications are tightly controlled. Everything's integrated and works. I'd stop way, way short of calling it revolutionary, though. It's a neat little toy...if I were spending the money, my iPad would look a lot like new shocks for the M3.