When we full-timed in our RV from 2002 to 2004, we used the Verizon cell phone modem. Even back then the speed was adequate... much faster than dial-up, but slower than DSL or cable modem. I don't know how much it is now, but back then it was $99/month - unlimited usage. If you knew how much time DH & I spend on the internet, that was a bargain!!
A friend of ours lives in a very rural area where there is no cable or DSL available & got an air card when they first came out. He's a real computer geek & said the speed was much faster than he anticipated.
If we go back to full-time RV'ing (if our house sells) we'll probably get one.
Anyone know if you can set up a network using the air card?