Just got the Leap yesterday after finding it on ebay for $45. The piece looks nice and it comes with two cords. Nifty idea, but a silly waste of money. A tie or a rubberband can control the size just fine.
Hooked it up to my mac mini (2011). Here was the first issue. I didn't have an open port! With just four ports, being used by the keyboard, mouse, camera, and kindle, i disconnected the Kindle. We can share on that port. 
Downloaded the software and went to the playground. After a short bit it warned me of a smudge. Nice! Got that cleaned and continued.
I use wrist stabilizers on both my hands when using the computer. These seemed to obstruct hand recognition. The leap kept misunderstanding whether i opened my hand or not, and in which direction it was facing. The stabilizer does not cover my fingers, so i wonder if there is any hope there. Anyway, i took off the stabilizers to continue,
After the stabilizers were removed, the recognition was better, but not perfect. Not by far. The system mostly knew where my hands were and to which direction they were facing , but opening and closing the hand, and especially grabbing things, was difficult to have recognized. Placing the heads on the dancing robots took a long time and getting my digital hands to reach the front, back, and sides of the room was not an easy task. Even after holding a box, half the time it fell or got flicked away. Not that this wasn't fun, but it just seemed so unreliable.
Placement of the device is a problem of its own. All the pictures show placement on a desk in front of the keyboard. I don't use a desk. My monitor is on top of a container holding it a foot or so off the floor, my mouse is on a container to my right, and the keyboard goes on my lap during use. Otherwise, it is leaning against the right side container. I find this so much more comfortable than a desk, both for my arms and neck. So, where to place the Leap? I tried near the mouse, which was a bit of fun, but getting my left hand all the way over to the right is not ideal. My legs can hold it quite well, but it inadvertently gets shifted around and changes position unless i am very careful. The floor seems to put it out of range. I kind of settled on the monitor stand, where it works if i lean forward, and put it on my lap for some of the time. This is a work in progress.
I went to the games and downloaded some of the free ones (didn't see a sorting option). Moving the line through the dots showed the system missed where my finger was a minority of the time. Catching and balancing falling shapes was fun, but the platform shakes too much (was that the detector or my hand?) The centipede number game looks like it might be fun for my neighbor's kids. It had the best recognition of where my hand was. The oversleeping alien was well put together (except hiding the fact it is only a demo) but i had a difficult time shooting, due to non-recognition of the forward move. All in all, the games can be quite a bit of fun, though they don't seem to work perfectly for me.
After reading about low light being a problem, and seeing an option in the software for it, i tried holding a flashlight to aid recognition. I don't think it helped. But, i also had no idea where it would be best to hold so i tried here and there before giving up. If low light is an issue, why doesn't the Leap include a led light in the device to illuminate the area?
Due to the issue in recognizing hand motions, knowing what the range is, and seeing if light helps, i would like to see a test tool (maybe its already there) specifically designed to show what is recognized. Learning it from games is fun for the most part, but a tool would make it easier to test the extremes.
I'm happy i bought this on ebay. The full price, and even the 25% off, to me, are too expensive for the semi-working toy. Granted, the issue maybe my system, my lighting, and my hands. I am not complaining about the Leap itself, per se, but my experience with it. At $45 (included shipping) it still seems expensive for a toy, but it's okay. I certainly don't regret buying it! I knew what i was getting into, and i'm going to enjoy the ensuing fun. Now i just need to learn java and use the sdk.
