Hello, I use this keyboard!
I had to intentionally practice for a couple of weeks before I felt really comfortable typing. When it came to typing symbols I've always been a cheater, so the shift+numrow symbols were the hardest for me to remember.
Replacing the modifier switches with loud and clicky ones helped me get the feedback needed to allow me to type combinations quickly (and ZSA optionally sells a secondary pack of ten with your purchase, just enough for the mods/space/enter/esc).
The arrow keys should be familiar to anyone seriously using vim / vim bindings, as they're in the same hjkl configuration.
The thing made hardest with this keyboard is actually video games. There are fewer buttons in the range of one hand, so I often end up remapping some buttons to my mouse if I have to. The ctrl/z/x/c keys are all pretty hard to press when your hand is on w/a/s/d. For games that fully utilize a keyboard (Space Engineers, GMod, etc) you will find yourself making layers specific to those games.
This all being said, I don't have the largest hands and I enjoy that my wrists basically don't have to move around. The customization is a treat. I actually take it with me to work and back home, because it's so small and easy to move that I don't mind it. Also I made a numpad layer that I'm really happy with, and that only works on an ortholinear.
The price tag is serious, but the keyboard is hand assembled by well paid workers in Taiwan. For the amount of time I spend typing on my keyboard (at least 8 hours a day, every day) I'm perfectly happy to dispense with some money for a solid product.