I have one ukulele, a Risa Uke Solid Concert, with very thin fret wire, compared to any other ukulele I have. I believe the thin wire is one of the things that makes the instrument easy to play, being that you never have to squeeze to fret a string, and the general feel of the low fret wires makes movement across the fret board smooth and easy. I also think it's one of the factors that give the Uke Solid really exceptional intonation when playing. Push down as hard as you want and you don't change the pitch as much as you would when the string has more room to travel between the top of the fret and the surface of the fret board. The only drawback I see is that a little more care may need to be taken to fully depress the strings to reduce the chance of buzzing when barring, because your finger doesn't have any extra room for give. The soft portions of the finger don't squish down as much in that smaller space, leaving a somewhat greater possibility of one string being in a finger joint that isn't quite down far enough. It's not hard, with practice, to eliminate this problem, so it's a small negative, in my opinion, but might be discouraging to a beginner.