What the hell are people printing that is so important you want to print when the power is out?
I didn't even considering plugging my printer into my UPS... But clearly I'm not the reviewer.
It's more important that you have your PC on a UPS so that it can be safely shut down incase the power actually goes off for any long period of time. I thought that's all a UPS in a home environment was ever for? A workplace/server is another story obviously.
I could see it being useful if power goes out at the wrong time and you need to print a document for school or for work.
Although really if I had power on my computer, I'd just copy the doc to flash drive and also email it to myself and print at work...