Quoting Edward Diener eldiener@tropicsoft.com:
I don't know what you mean by "windows software behavior" but if I am working with the screen in front of me and the A/C power to my UPS goes out or the system needs to shut down because the A/C power has been out and the UPS battery is running out of power to support my continued working, I like to experience some sort of notification when these things are happening. Since I am staring at my screen, a visual notification seems justified to me. If that seems unusual to you then I can only surmise that you use your computer differently than I do. Nonetheless, since it's each to their own, a visual notification is what I would like to alert me to what is happening.
What about that annoying periodic beeping from the UPS when the power is lost? The entire house all the sudden dark and quiet. I don't know. Usually there's so much indications that power was lost around me. The windows popping up on the screen just to tell me something my senses already detected is, well, annoying. But that is only my personal preference. I guess. However, it would be nice to have power meter for battery in the tray, like the one for laptop battery.
The warnning couple of minutes before machine starts to execute shutdown sequence (or with FC6 and RHEL5/CentOS5 save to disk) is nice thing to have. But that part is relatively easy to implement with apcupsd.