Oooohhh gosh where to start huh? The world would be nothing like it is today, to say at the least. Many of those who held power, had horrible intentions. They manipulated people, who trust them. Who may have voted them into office. They abused it. Power and Control is an important "idea" to think about huh?
Life would be filled with disaster. BUT, then again, it would be good too. Depending on how you look at it. You could look at it as a positive, seeing that one emperor would mean only ONE perspective. So one way of ruling. But, they would have ALL the power and control, and would lessen our changeability and we may all very well be robots...
This question, should really be from YOUR perspective. Because, it may likely vary drifting from person to person. From perspective to another.