Too bad their coverage in smaller cities and rural areas is still pretty bad.
At least in areas where Nextel had a serious presence.
The solution is only use TCP networking (UDP transit is intentionally FUBAR) and EasyTether Pro on stock Android.
Check 4G coverage with cellmapper.net
Make sure your phone supports Band 71 - it's everywhere nowadays - and band lock your modem to band 41 for crazy speeds in congested metro areas.