Amazing little device
This device does not replace your keyboard. It offers you extended control with real-time continuous controllers, faders, wheels, and switches which all work very sensitively and are easily configured.
The keyboard has "half-action" which does not respond like a fine Kurzweil, Yamaha, or Roland, but it was never meant to replace those. And yet… I often get just what I need from it in spite of its limitations. You do get used to it.
But this instrument just has so many things going for it: it's USB and is automatically recognized by your Mac, the knobs can be "speed-controlled" with the side of a finger, or multiple fingers on multiple knobs, giving you a lot of simultaneous control over complex virtual instruments like Wallander Instruments or VSL. You can hang it from a guitar strap and wear it, giving you extra control even while you're playing your Kurzweil. There are many more features; I can't name them all. Trust me, for under $150, this thing ROCKS.
This is not a first keyboard for beginners, it's an additional keyboard for pro's who know what they're doing, what they need, and how to get it. In that capacity, there isn't anything available that even comes close to this. No, you're not going to play the Minute Waltz on its keyboard, but it wasn't made for that. Use it for its strengths, and you'll be a stronger and more productive musician in the electronic studio.