It has several of the same features that Energy Saver has. Power Manager 3 can put your Mac to sleep, shut it down or start it up (or wake it up). However, the level of control is more precise. You can open the Power Manager 3 window at any time and select when your Mac should sleep. You can even select a time for it to log out of a certain account (I can see this being handy for parents who want to monitor how much time their kids are spending on the computer). Another helpful addition is that you can set up Power Manager 3 to alert you before an event takes place. Therefore, if you forgot your Mac is supposed to shut down at 12:00 PM and you are still working, at 11:45 PM it will let you know about the scheduled shut down so you can either hurry and save or cancel it.
Power Manager 3 also allows you to set up a schedule for your Mac. You let it know your normal schedule and it starts up and shuts down (or sleeps) accordingly. I can see how this would work for a school computer lab or even an office, but for home use it's a little less important. My schedule changes everyday. Therefore, I set up what I thought my schedule would be. Then, when Power Manager 3 alerted me it was going to shut down, I had to cancel the event. Unless you adhere to a very strict schedule yourself, you might (as I did) find it more constricting than helpful.
The only other problem I have is that Power Manager 3 does not work with Energy Saver. If Power Manager 3 could import your Energy Saver preferences and the two worked together instead of separately, I might find Power Manager 3 more useful .
