So I use the 0-Ctrl as a keyboard a lot, even though I have an Arturia Keystep, I highly prefer it to an actual western keyboard because it encourages you to make different, non-linear, note choices.
Like I another poster above, I also use this in combination with a Pressure Points and an Ears, and they were totally right, you really have everything you need with those three things in terms of control. I also have two quantizers, a Penrose and a Marbles which are used in conjuction as well. This is the heart of my control setup. I actually use this to play a 4u banana Serge setup, and it works beautifully, I just made a bunch of cables that go from euro to banana.
So, my only gripe about the 0-Ctrl, which I do find annoying in some cases – I wish the envelope that is tied to the pressure output and the dynamic output was adjustable. I find when playing the pads, the attack and release is a bit on the slower side, especially when compared to PP. Its really nice for slow swells, but not as nice for faster playing. Also, when you are sequencing, I also wish the envelope decay on the dynamic gate output was snappier. Oddly, you can adjust this when the 0-Ctrl is externally clocked, by adjusting the speed all the way clockwise, but then you loose the ability to have the bottom row make adjustments to the speed of each step. So, that’s my only gripe… adjustable attack and decay would have been nice, even if it was with a trimpot, maybe there is one, I just didn’t see it at least.