The colors are nice, i also like to enter (a few) candidates myself like on paper.
But the 3 evil puzzles i tried were all easy, needing nothing more than locked candidates and pairs.
So when you ask for more techniques to implement: triples, x-wing, xy-wing, xyz-wing, quads, unique rectangles (types 1, 2, 4), y(w)-wing, BUG, coloring (2 strong links, 3 strong links), unique rectangle type 3, swordfish, unique rectangle type 6, multicoloring, ...
added 2008.Aug.15 by Moderator (Pat) --
i've now locked this Topic,
any further comments should go in
"Color coded sudoku"