Brilliant idea and a real time and pain saver! I believe that I will be happy with this purchase for many years to come, since it eases up a task that is very time consuming and cumbersome otherwise.
I was unimpressed (yet not surprised) with the chinese quality of this tool. but the price is right and will do the trick anyway. So no complaints in that department I guess.
The tool sports ample power for its task, and batteries seem to last long (already used it on several restringing duties and I can only guess).
Another con (admittedly subjective and not vital to ditch purchasing this fantastic idea) is the size. This "drill" is vastly larger than I expected (say 70% the size of a household usual drill). So size is less than ideal to consider this winder comfortable to keep with you at all times in the case. Then again, this will usually find its place at home so it migth not be a factor for you.
In short: is a fantastic idea that renders a painful job into something fast and easy, looks and feels like plastic, is tolerably fancy looking, is large and eats power within reason. A clever purchase!