The CEO of Leap Motion announced on the forums that they will delay the ship date by about a month.
"I wanted to post here to update you guys on the status of our ship date. After a lot of consideration, we’ve decided to push back the date and will now be shipping units to pre-order customers on July 22nd."
They cite worries over not testing enough as the main concern for pushing the launch date back, but they also mention a beta Airspace for devs, and they might possibly send devices to some non-devs for this beta test.
"The reality is we very likely could have hit the original ship date. But it wouldn’t have left time for comprehensive testing. This will come in the form of a beta test that will start in June. We will give the 12k developers who currently have Leap devices access to the feature complete product including OS interaction (today developers only have access to the SDK). We will also invite some people who are not developers to join the beta test."
Overall I think the software behind the device could use some work to improve persistance and tracking. I am also looking forward to more features like access to the raw data, full skeletal tracking (even when your hand is blocking some of the rest of your hand), and better tracking under different lighting conditions.