"Hey so LeapMotion is still being developed, I better hurry to write a blog post and complain about it before they improve it".
If you take someone's money and give them a product they have every right to review it and point out both the good and bad points about your product.
I thought the review was very fair, and I"ll be the folks at leap would to. They just got a bit of press and some tips on what one of their clients thinks is broken.
Most people make sure their product is useful and working before selling it to people.
If you bought a car and the brakes mostly worked, would you be happy?