The AI does a proper job and usually is better or equal to your own command. This is also the effect of much less influence and decisions you have and can take of course.
In the beginning I controlled all my combats, but since the AI empires got better technologies and since you had to search a long while for the enemy before engaging due to cloaking, ECM and such, I often select cede or watch.
I cede the battle if there are clear odds, I watch a battle if it´s a bigger one and therefore interesting.
And I control battles against guardians or a New Orion fleet with my 68 ships against their 40 ships.
My guardian defeater fleet is rather specialized, with 5 TFs of scouts, 2 LR and 2 IF. So I control them, in order to keep the IFs far away from the guardian and to send my scouts in all directions to find it.
The main HUGE advantage and in my opinion a bug or at least something that makes controlling less fun is the point that when you cede or watch, all FIGHTERS and MISSILES are started immediatly and you fleet heads into the correct general direction of the enemy. So once that is detected, all fighters and missiles rush into the enemy fleet at once.
When controlling yourself, you can only fire once you see the enemy, which is a huge disadvantage I think.
But still, in major battles I love to take control. After all, it´s the only real part of the game you can control without (much) AI interference.