Chairs weren't hard at all. I spent more time getting the seats off the chairs than I did covering them. All you need is a staple gun and some 1/4" staples. It goes pretty easy, but I have to say that my hands got kind of tired from stretching the fabric and working the staple gun.
My mom and dad did a set of chairs many years ago and my mother went on and on about how hard it was so I never tried it. I lived with these chairs with old peach covers on the seats for over 10 years because I thought they would be hard to recover. Then I had some bed steps that my dog uses to get on the bed that were old and stained and I wanted to recover them so I tried it. Once I found out how easy it was I decided to do the chairs, too, and I'm so glad I did.