Yes, if it says 3G, you can download anywhere there's a signal. That's what I have. I did buy my husband one, without the 3G, because he doesn't travel as much as I do, and we have wireless in the house.
It is so great to be on planes as much as I am, where I freak out if I don't have enough reading material, and I can make a quick decision on a book to buy for the flight and download it before the flight attendant says, "The cabin door is closed, please shut off anything with an on-off switch."
I agree with spending the extra few bucks to go ad-free, if you can.