I would say that it depends on your intended application. If you are going to be doing a lot of long distance hauling, I would say no - go with a more modern truck. If it is going to be shorter trips, more at your leisure kind of thing, I'd say go for it.
I started looking for a dump truck in the winter and couldn't find anything in my price range. I ended up with a 1970 Kaiser Deuce and half that I am going to install a hoist on this fall (if I get around to it). I can tell you, from my experience, there is some truth and some misconceptions that have already been posted in this thread. If you are serious about getting one, check out
Steel Soldiers, and it will have all kinds of information about the deuce, 5 tons, and other military vehicles.
I drive mine around the farm and relatively short trips. I drove it home (about a 2 hour trip) and I personally wouldn't want to drive it a lot further at one time. However, I expect for about a 30 to 40 mile trip (one way) to be about the furthest that I am going to drive on a normal basis.
Don't get discouraged about it, but don't go into it blindly either. Very good trucks can be had for very low dollars, but you may have to contend with weeding out a few bad ones (just like buying any other used vehicle.
Good luck and take care.