10 bans is comming and it is not the preemptive bans so many people were hoping for.
http://wwg.com/2017/01/05/riot-formally-announces-10-ban-snake-draft-for-competitive-play/
They are reactionary bans instead if you chose to use them as such.
And it is more then likely going to end up like this for everyone and not just competive.
Pros?
You can try to screw up the enemy teams champ synergy. Get rid of janna when they get Yasuo or stop the Ori cow ball delivery You can target ban something that the enemy team has not picked yet. Enemy jungler not picked? Ban that Lee and Hec since they are still up and your team already got Vi.
Cons?
You can not be more likely to out right ban Yasuo or any other champ every game. This is not even really a con in my opinion but I know a lot of people will be bitching about this not being the case.