This is an awesome app. No doubt it'll save some battery life during the day when you don't really need the back light on for your keyboard. One tweak that makes this really useful is this - import the following registry file using a registry editor. What it does is make your side key thats below your volume rocker usable for a single press in addition to being able to press and hold it. Assign keylight to it and you have a quick easy way of shutting off and turning on your keyboard back light.
Here's what's in the registry file, and I'd import it instead of typing all this in. Just easier, imo:
[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shell\Keys\4 0C7]
Default="\Windows\Start Menu\Camera.lnk\"
"WndCls"=""
"Flags"=dword:00000000
"BtnWnd"=dword:00000000
"Name"="side"
"Icon"="\\windows\\shellres.dll,-8263"