Your link is to a 2115 which is a 3/8" impact. Farther down the page, they show the 2135 which is the 1/2" and which most would want. My personal impact wrench now is an IR231 that I got at a pawn shop. There are lots of cheap impact wrenches and if you read the specs, get one with enough power, and keep it lubricated, it'll probably do just fine. If you want one for which parts are available if it needs repair, Snap-on is good if you don't mind paying double or triple for any parts you need, otherwise go with Ingersoll-Rand or Chicago Pneumatic or MAC, Matco, etc. that are made by one of those.
I posted that one because it would probably do more than what the average home owner/ tractor owner would need. Alot of people would probably get their selves into trouble with it. I very rarely have to use a 1/2 and a wrench for a living on automobiles. I guess for another $20 it would be worth it to go to the 2135, it just won't get into the places the 3/8 will.