I switched my fleet of cop cars to Verizon cards (from Sprint) earlier this year and could not be happier. Granted, the usage is pretty much limited to our municipality, but we are seeing better throughput and less dropped connections with Verizon compared to Sprint. Customer Service has been much better on Verizon too.
The smart phone tether option is worth exploring. I have that option enabled on my BlackBerry (a $30 up charge on Verizon for a 5 GB monthly limit) and have it used a few times.. Getting real Internet access at our hunting cabin in the swamps was something none of us expected to work, but it worked fine with the tethered Berry. If I was using it a lot (daily), I would probably opt to go with a dedicated card. Even though there is a pretty hefty up charge tethering, it's not something I have to have on my plan for the whole year. I will keep it during hunting season, but then cancel it. When it's vacation time, I'll likely add it back to the plan so I don't have to rely on wifi hot spots.