Pro. Hibernation turns your computer completely off.
Con. Hibernation closes your internet/ethernet connection. (also does this in standby)
Pro. It saves everything in memory to your hard drive.
Con. I'm not sure of the risks, but data corruption is a possibility.
Pro. Your computer starts up much much faster than with a complete re-boot.
Con. Your computer won't be as quick, and you won't get all of the perks like you would with a re-boot.