Gurn your way to the top
The unfortunate side effect of using the NIA is the complete fool you will make of yourself if anyone is watching. This thing will have you pulling all sorts of odd faces just to get the right responses.
Being a respectable media contributor and a professional, I invited my friends over so I could laugh at them trying it.
Their opinions were ranging, with some finding it easy to get used to and some who just couldn't work it out; and one person who had some strange bodily generated electrostatic field that just messed with the readings no matter what, so we couldn't make it work for them.
All the while, it is important to maintain the perspective that this technology is in its relative infancy for a commercial product. Concepts rarely supersede each other overnight and take time to come to maturity.
A bit of searching reveals that this unit is currently on sale at Newegg for 79.99 USD after a mail-in rebate, so there is no excuse not to try one if you have the readies.
We are entering a new era of human machine interaction and Myo-electric control is certainly on the cards as a viable solution. For those who want to get in early on a piece of technology that works and is affordable, I can recommend an NIA to you. Just be prepared to spend time using it to get the most out of it.