I have these myself, and they work wonderfully. To programme it, design your layout with keyboard layout editor and copy the raw data to the TKG keymapping GUI. It's pretty intuitive. The 3 LEDS do the same as the LEDS on normal keyboards, indicating whether caps lock is on or not etc. If you use clear acrylic for the case, lights will show through.
Another note - these are aimed to be an improved version of the original ergodox. Namely, the controller is on the left side rather than right like the original ergodox. So you can use the left hand on its own while gaming, which saves you some desk space
Also in order to flash a new keymap, all you have to do is hold a key while plugging in the usb cable. The original ergodox and even the infinity ergodox require you to open up the case in order to press the flashing/reset botton. And ergodox's cases take quite a while to open and reassemble, given the amount of screws