Yes. The keyboard has 8 levels of brightness: "1" (dimmest) through "7" (brightest) with "0" being off. To change the brightness level, press and hold the "Fn" key down and press the "up" or "down cursor" keys to brighten or dim the brightness respectively. With the "Fn" key held down, if you press one of these cursor keys, the brightness will step one level in the corresponding direction. If you continue to hold the cursor key down, the level will continue to step in that direction at a rate of about 3 steps per second. However, there is no "roll-over". For example, once you reach maximum brightness, the brightness level will not "rollover" to off and then continue getting brighter.
No information will be sent to the PC while the "Fn" key is held down and either the "up" or "down cursor" keys are pressed. In other words, the keyboard doesn't tell the PC these keys are being pressed. It also doesn't matter which key you release first. However, any other key press will be reported to the PC regardless of the state of the "Fn" key.