Overall, it's a decent tool for a really cheap price. The tool itself is a bit stiff for my liking, but I'm not gonna dock any points for that.
However, do be aware of what tuners you have on your guitar(s), because the string winder doesn't fit all sizes. If you are a bassist, you have nothing to worry about. But if you have guitars that aren't modern tuners with wider, flat buttons, the string winder will just barely do the job. If you have any guitars with vintage tuners, it won't grab the buttons at all.
But it also only cost three bucks, so it's not exactly a major investment.