With the addtion of the Celtic knots, this version of KP is even more useful for creating beautiful to weird knots that export to 3d applications. I suppose if I was a "math person" I'd appreciate the visualization of the formula's that make knots possible but I'm an eye candy person instead - and there is still plenty for me to appreciate. I do like the grid info for the Celtic knots! I remember drawing those out years ago...

The animated knots are great - wish the animation data could be exported.

The interface is a little intimidating/programmer-y but is easy to use. However, it's well docuented.