Is it worth it for me to start watching Sherlock on Sunday when the third season premieres (on PBS in the U.S.), or will I be completely lost? I haven't seen the first two seasons and, admittedly, the only thing I know about Sherlock Holmes I learned from Wishbone the dog. (And from the bits and pieces I've picked up in GT).

I guess I'm just wondering if this is the type of show I have to watch from the beginning or if I can dive in halfway through. I would've started watching from the beginning but I had no idea it was airing on American TV.