The wound low-G rings quite a bit longer than the unwound ones, and then there is the squeaky noise when you move your fingers along the strings. Not nessesarily a bad thing, it makes the playing sound more guitar-y, but perhaps not what you'd expect from an uke.
The low-G string i quite a bit thicker than the standard high-G that ofthern comes with the uke, so a little bit of filing, sanding is required to get the string into the neck-slot, so as not to make the action even higher.