Really difficult to set up, since there's no indication of rows, but it matches nicely with my keyboard, and I've learnt touch typing as a side effect.
The simple, nearly unmarked design looks good, and the product's greatest advantage is that it can be used with a variety of key layouts.
The thickness and quality of the keycaps are also high, as is expected from GMK, leading to improved key feel and keystroke sound.
As someone who doesn't look at my keyboard while typing, I pretty much liked the idea of using blank or non-alphanumeric keycaps just to piss people off. Yes I'm a posh and I don't often like sharing my keyboard to mah friends. The pixel design is just blanks but with extra steps and I love seeing my keyboard with this set on.