So my friend got one yesterday and I got to try it out for the first time ever. He got with the intention of playing with the SDK and trying to release a game or app to the leap motion app store.
I was slightly unimpressed with certain aspects. Certain movements worked really well. Like side to side/updown directional pointing.
However if you have to move your hand forward/backwards for things, often you will go off target.
Additionally, if you try to pinch something, you often go slightly off target.
Both of these are my own human's fault, not the device's fault as it registers my position accurately. Humans just aren't meant to have free floating in mid air precision. We have high dexterity with hands and wrists, but when you involve an elbow and shoulder, all precision goes out the window.
I think ultimately the fault will rest in the humans for being to unable to deliver the right kind of precision in the right areas.
However for 'rough' or coarse movements. It works beautifully. The 3 finger swipe to switch tabs or scroll pages all work just fine.
However for general course movements, do you know a $50-80 device? Probably not.
I personally think that this device could be dropped in price to less than $20 and incorporated into computers/monitors or whatever as a secondary or third controller. That it could have a little use on occasion. However, I don't think it'll ever be a 'primary device' controller.