Since nobody has mentioned it yet here, I'm really glad to see AirDrop will finally work between OSX and iOS. It's bothered me for awhile that they have these two different things called "AirDrop" which were not compatible with one another.
AirDrop pre-iOS8 (iCloud Drive, Extensibility) would have been almost totally useless or at minimum required developers to waste time supporting a temporary solution.
My understanding is that on OS X AirDrop was wi-fi only but on iOS it used a combination of wi-fi and Bluetooth.