I had used smoothcam with some older SD projects and it did exactly what it was supposed to do.
I have tried to use it in a current HD project and it just looks awful. Jumpy, grainy and completely unusable with regard to how much it degrades the footage. I mean, it looks like 2nd generation VHS footage! Bummer.
I'm sure I may have to provide additional info, but I'm not sure what settings would be required to help solve the problem.