I've been using it and its a great add on.  In addition to finding any tri's or ngons in mesh and auto selecting them so I can easily see them and fix them; it also finds open edges (useful for when you are building a "water tight" mesh) or inward faces (I'd screwed up on a current project and had accidentally created a face on the inside of the mesh connecting opposite sides of the surface topology which would have cause problems.  Mesh Lint caught it for me.   So yeah, very useful.