The ability to have tabs in Apple OSX’s Finder alone is worth the price of entry. I’m terrible for having a gazillion Finder windows open at once; this helps me really keep sensibly organised.
A main focus of the project is to add a dual panel mode (like in good old Norton Commander) to the Finder. I was never a Commander guy, but I’ve heard many folks longing after it, and nearly every FTP program uses a similar interface.
Hey, why are you still reading this? Go get TotalFinder already.