THE GOOD: The good thing is that when you put the same ranked prisoners together they can cope better with each other, and they seem to get into less fights. Since there will be less fights, your prison reputation with be higher and the other Wardens in the game will envy you. It will say that on your message box that you have in the middle of the game screen.
THE BAD: If you don't separate the same ranked prisoners in their own part of the prison, where it is gated off, you will have to deal with a lot of riots nonstop and you will have a lot of prisoners dieing and that will be taken out of your funds.
And the prisoners don't cooperate together when they are all in the same area with different ranks of prisoners, especially the Maximum and High Security Prisoners with the Medium and Low Security Prisoners.
SUMMARY: It is fun having riots though. But, having a riot one after another is a pain in the butt and it takes out the time of the prisoners lives, because sometimes the riots go too...