Just did a speed test and it's 31Mbps download and 4Mbps upload, but it varies wildly by location. But it's consistently fast enough that I can share out over Wifi from my cell phone so I can do my work and while my girlfriend watches youtube videos when we are travelling or the internet is down.
For home internet.. once it got faster then my wifi I stopped really caring a whole lot. 176Mbps on my last test.
If you are travelling in the USA as long as you stick to the interstate system you pretty much get mobile data the entire way. IF you drift onto smaller highways then that is when things get very spotty outside of metropolitan areas.
Verizon tends to have the best coverage in the mid-west. If I was travelling a lot in the boonies I would get a second data-only account on Verizon's network just to increase my chances of always having internet.
Although nowadays that is less and less necessary as every hotel and most restaurants have wifi. Just look for a Mcdonalds and you can get internet most of the time.