That is all I have for internet, not necessarily by choice as cable and DSL are not available at my house. I have a Kyocera KPC-650 EVDO PCMCIA card, with a KR-1 router at home (purchased at AT FS/T), and my service is with Alltel. While it certainly beats the pants off of dial-up, there is a ton of variability in speed. I have hit speeds of up to 1.6Mb down/225Kb up, but the test I ran just now is 817Kb/104Kb (latency of 232ms). I will say that it does work pretty reliably for VPN which is a good thing, and speeds with the current gen of hardware should be better.
EDIT: Oh yeah, cost. Check with your employer to see if they ofer any kinds of discounts with wireless providers. Mine offers anywhere from 10%-20% discount depending on the carrier (15% with Alltel). Also, you might see if you can get in on the SERO plan still or not.
Alltel's base rate for unlimited usage is $59.99. I can't say definitively that it is unlimited, but I have at least 5 machines at any given time - doing stuff like Windows Updates, downloading ISOs of my TechNet subscription, etc - and I haven't ever gotten a nastygram from them or been billed for any 'overage'.