I have three APC UPSes at home.
I have a couple of rather old six-outlet Back-UPS ES 350 units for things that don't draw a lot of power (like my DSL router and AirPort Extreme).
I have a slightly better eight-outlet Back-UPS ES 550; this one has "green features" which has a master socket that will control the power of a couple other sockets. Thus, when I turn off the computer monitor, it will cut off power to two other devices (in my case a stereo amplifier and a powered subwoofer).
As the others say, there's a USB cable that enables the Mac's UPS management features; do not install the third-party software. I have my Mac mini set to shut down when the UPS battery level drops to 5%. It has never had to do so, as power failures in my neighborhood are infrequent and rarely go longer than an hour.
APC makes fine products, I have been a happy customer for 15+ years.