I've been driving trucks for a little over 4 months now. The big trucks that everyone hates on the road that go slow up hill and slow past each other blocking traffic. Trust me, I hate it even driving the truck.
I can't say much about the company I drive for as I have no idea how other companies do business, pay or run their drivers, etc. What I have heard though, is that they are the lowest paying of them all. But again, I don't actually know for sure, or at all, about that.
I went through a 2 week class to get a Class A drivers license. Honestly, unless you're a friggen tard, anyone can pass it. They practically pass you through the class, providing answers, and sometimes ignoring things that you should fail for. Understandable since they get money from the government for putting people through the class...but scary for the fact they will be on the road driving a giant death mobile (with the wrong driver of course).
The major downside to truck driving...assuming you have a social life...is the fact you never go home. You live in the truck as you drive all over the country. This is until you have the experience (or connections) to move get a local driving position. Seriously though, you have no life. You drive, you sleep, you drive some more.
The more setup drivers have a tv, possibly a gaming console (I have an Xbox), and buy a lot of movies. Some will even have microwaves for food, but I've always enjoyed eating out, usually fast food though. Another downside is a lack of a bathroom or shower. Most of the time, you will be stopped at a truck stop at the end of the day for showers, but not always. And the bathroom can be difficulty or far between when driving down the highway.
Being a more solitary person, I do enjoy the job, but I miss having a decent computer and time to do the projects I enjoy.