A while back I did a post on the YN-560-II, and how it is a good all around manually triggered flash that you can use if you are using Scott Hargis's Lighting Interiors manual flash technique. For details see Lighting Interiors e-book or Scott's Lighting Video series.
The YN-560-III that was introduced in January of 2013 is a slight refinement of the YN-560-II that has a built-in 2.4Ghz trigger compatible with the RF602/603 triggers. That is, when you are using Scott's manual flash system you need to trigger at least one flash wirelessly if you are going to get the flash off your camera and have one flash fire other flashes optically. What I like about the YN-560-III is it eliminates parts and batteries.
So the complete setup would be:
For those just starting out with Scott's manual flash system the YN-560-III and an RF603/603 makes a great first flash. It gets your flash off the camera, it triggers wirelessly without spending a fortune on triggers, and it minimizes parts and batteries. Then as you learn Scott's system and need to acquire more flashes you can acquire, SB-80dxs, or YN-560-IIs or YN-560-IIIs any of which can be optically triggered by the first YN-560-III.
The feedback I've gotten so far is that the build quality of the Yongnuo flashes is pretty good for the price and compared to the classic SB-80DXs. I have a YN-560-III in the mail to me to give it some testing. Is anyone else already have experience with the YN-560-IIIs?