I've used both and though Total Finder is currently free (until 1.0), Path Finder is more of a total overhaul, separate app and adds lots more features whereas TF adds onto Finder.
In its current state TF is more then usable, were I not to have purchased PF, TF would be more then adequate as I don't use a lot of the more advanced features of PF. The one thing that TF needs is cut and paste functionality, I think, which PF has.