I'm just starting out with wire work. I am not keeping everything I make (some of it is not very good), but it seemed silly to throw out the wire if I could re-use it. (For the record, right now, I am mostly using "Artistic Wire," the color-coated wire that this was designed to work with, since that is what I bought to get started. I have only tried this on 20 gauge wire. I suspect it would be more difficult to get to work on thinner gauges. I also have no plans to move on to gold or silver at this point.)
Anyway, pretty much all you need to know about the operation of this thing is shown in the inset photo of the woman's hands that you see in the product image. It really is that simple. Put the wire in, close the two outer rolls, hold the device shut, and pull the wire through. I love that the rolls are nylon; they really help prevent the color from coming off my wire. So far I have not marred the nylon as I work, either.
This is lightweight and suitable for use by people with small hands (which I definitely have). I don't find that it requires too much force. It doesn't always do 100% of the straightening I want, but it is pretty good and I can usually fix by running through a second time and/or deal with local areas using my nylon-tipped pliers. This does save a lot of time over trying to straighten wire with pliers; it is just easier to hold on to and keep in place.