That's the exact same thing as the one at arcademvs.com which is sold for $23.99 + ship. You might consider comparing prices.
I built a similar device a few years ago using a different design (same function), and quality was excellent with a good TV. Quality on a bad TV was, well, bad. Composite will always look bad. S-Video can look almost indistinguishable from an arcade monitor on a quality TV.
Note that these devices only work with standard res (CGA) games. They cannot be used with medium res (EGA) or VGA games. Most games, especially classics, are standard res.