I've had a Verizon MiFi 2200 unit for the better part of a month now. The concept is really simple: you press a button and the device creates a bridge between the Verizon high speed wireless network and your very own WiFi hotspot. Simple, fast connectivity anywhere without wires.
The short summary is that it does exactly what it claims to. I've used it throughout Seattle and the Eastside as well as several more remote parts of the Olympic Peninsula and have not had any issues at all with coverage or speed.
Setup is easy with a one-time install of the wireless management software for activation and it can be uninstalled after that since it's not subsequently needed. 'Unlimited' data plans are rather steep at $59.99 a month but the convenience factor is huge. My bus commute has become a lot more productive as previously there was only so much e-mail management or blog reading to be done on a small phone screen.
I have to believe the costs will drop as time goes by. Regardless, one thing is clear: this is like getting that first cell phone and once you're used to it there's no going back.