What Batman Really Thinks Of Every Gotham Villain

Clayface's powers make him substantially more effective than the ability to become a puddle of mud might suggest. Both his improved physical strength and ability to shapeshift into whatever form he wants are almost invaluable in and out of combat.

The only real shame is that he didn't decide to continue his work as part of the Gotham Knights. It's like that old saying goes: you can lead a clay man to the side of good, but you can't make him stay.