I'm currently using Verizon 4G using the LG VL600 USB modem on my desktop computer. I've been using it since February and it has been very reliable in a fixed location, other than the one day national 4G outage that Verizon experienced a month or so ago.
If you look at the coverage map at (plug in your address, then hit coverage map):
Verizon 4G Coverage Map
If you zoom out a bit, you will see that most of the area between Lake Weir on the north, SR 44 on the south, Lake Griffin on the east and US 301 on the west is covered by 4G.
The 4G modems and related software still have some bugs. I have locked my modem into 4G mode, as most of the problems have been related to switching between 3G and 4G mode. This might not be a good solution to a truly mobile application (using it in a moving vehicle). With mine locked in 4G mode, I have had no real issues, other than that nationwide failure mentioned above.
The speed can be pretty blazing. Using
www.speedtest.net, the highest speed I've gotten was 19.13 Mb/sec down, 3.98 Mb/sec up. Just ran a test and got 12.88 Mb/sec down, 2.95 Mb/sec up. A problem with testing is finding a remote test site that is fast enough to give an accurate result.
Probably my biggest problem is there is still a 5 GB/month quota, with additional gigabytes available at $10/GB. If you hit sites that automatically start downloading videos, your entire quota will be gone before you know it. I've turned off flash (in Chrome browser) as a default and only enabled it for certain sites as a result.
