Good Start. Make sure your peripherals can handle it
I bought this to reduce energy use. The basic feature is that it shuts down peripherals when the computer is shut down. This works, and is how I use it.

It also has the ability to shut down peripherals when the computer "sleeps." Unfortunately, when I wake the computer, the printer's don't wake up. As this machine computer handles the printer for the house, I can't this feature (would have to come and turn the printer back on all the time).

Now, I can't "sleep" the computer without shutting down everything. Haven't yet done the energy analysis of that...

Works exactly as described
I have 2 home-built PC's with MSI motherboards. I am using two of these APC devices. The relay works flawlessly when I shut the pc off, or put it in standby. I've only had the units for a few weeks, so I'm not sure about cost savings, but each PC has multiple electronic devices attached to it (speaker amps, printers, electric staplers, shredders etc)that all shut off when the PC goes down, so I'm expecting a decrease in power usage.

Do Not Believe The Energy Savings Statement
This power strip claims to save $25 on average per year but the amount of power the APC strip uses diminishes any of the energy it saves on the peripherals. Therefore, buyers do not see the reduction in their energy bills. I switched over to the Smart Strip by Bits Limited. This draws less than 1 watt when on and close to 0 when off. You can check it yourself with the Killowatt meter as I did.

No Good for Mac
I have a Mac Pro with 4 HD's and an 23" Apple Cinema Display. With the Mac Pro plugged into the Master and the ACD into one of the "controller by" outlets the unit does not operate as advertised. Putting the Mac to Sleep turns off the ACD and puts the Mac to "Sleep"-- 2 seconds latter the machine wakes up.

Their tech support confirms that unit will not work with my setup. Called their tech support originally, however, and they sent me out a replacement unit. Of course, it too does not keep the Mac asleep.

Not for use with iMac
While this is a good quality product that may be useful for PC, it is not a good unit for Mac. When the Mac goes into sleep mode the P7GT shuts down any peripherals plugged into the controlled outlets , this creates a small voltage surge on the USB line as the peripheral shuts down which immediately wakes the Mac back up.
In essence it creates a cycle that never lets the mac stay in sleep mode.