There is a review on Avsim of FS Repaint at http://www.avsim.com/pages/0306/FSRepaint/FSRepaint.htm
In addition to the review, I'll add my two cents. It is absurdly easy to use and has the benefit of letting you see your "finished" work as you go, without having to load FS. It also modifies your aircraft.cfg and saves the new textures in the right place.
The downside is that it is not the most sophisticated editor and the default palette has too many "lolly pop" colors. Fortunately, it can be used with an external editor and you can change the palette.
I get FSRepaint last weekend but i hadnt the time yet to...''play'' with it seriously.As a first touch i have to tell that seems like an easy to use program.
Beware of my future repaints...