I've been using a FlashAir II (and their accompanying iOS app) since Christmas, and I love it. It doesn't have the same problems that the EyeFi has – specifically, the EyeFi will only let a photo be transferred wirelessly to one device, and then it can't be transferred anywhere again. That was the deal breaker that led to me trying this instead, and I've had no issues whatsoever. These are a stop-gap until all cameras have wireless transfer built in, but if you're in the market to add that to a DSLR, get this instead of an EyeFi, and especially instead of Nikon's bulky wireless adapter that sticks out of the side of the camera.
