I got a chance to play with these yesterday. Just step in and out - no riding.
They look good. They'll probably work fine. The locking feel is better than the step-ons. With the step-ons you really have to pay attention to that second click. With these you feel locked in as soon as you step in. Stepping out is pretty much the same as the step-ons. Not as easy as the videos would have you believe, you really have to lift your foot out. When you're locked in, just like the Step-ons, you feel locked in. I don't think there's any chance of them coming "undone".
Other than that they have same downside as the step-ons: a really thick heel loop.
For me, I'll be staying with the Flow NX2s. Between the Flows, Step-ons and Supermatics the "step in" process takes the same time for me. On the Flows I stop, dig my toe edge into the snow, shove the foot in and lift the back. The step-ons are the same but I dig the heel edge. I think the Supermatics feel very similar. For me the only real difference is the heel loop that is just so massive on the Step-ons and Supermatics.
YMMV
Here's another review of the Supermatics if you're interested:
One more thought... The setup is very familiar to anyone who has ever set up Flow bindings. I think that people who can spend the time to set up the Flows properly would have a good time and those who have not been happy with Flows will find the same frustrations. Something to keep in mind.