just got them today, so I thought I'd post some impressions. First thing that jumped out at me was that the top LEDs aren't bright at all. I semi-expected this since the LEDs are mounted on the top while the caps are front facing, but even with the caps off, the LEDs aren't bright at all even in my dark office compared to other backlit keyboards I own. I have not found any brightness setting at all, although it is possible to run the unit with the LEDs off. Otherwise, the build quality seems to be pretty good and the bottom has nicely padded feet and even the angled feet, which I didn't expect at all. Oddly, the Esc/F row keys have blue LED as opposed to the purple that is shown on the main page.
As for "functions", F2+F1 cycles through the lighting mode for the top LEDs, which has a decent selection of reactive lighting and breathing modes, although since the lights are a permanent gradient, it isn't too fancy. F2+F3 cycles through the lights on the bottom LEDs, which by the way is much brighter than the top LED. This just cycles through a few different colors and there is a seizure mode where it flashes through all the colors without any fading effect and much too quickly for me to consider using.
Additionally, if the F2 isn't held down, F1 also acts like F5, or the refresh page button on a web browser and some other apps, while F3 acts like the backspace button. I like this touch, especially the F3, as it would be handy to have a way to backspace quickly if you typed the wrong number, so that's a real nice surprise. Other than that, it looks like this numpad has a nice standard layout so it should be compatible with most aftermarket keycaps.