Pros:

Great against ADC heavy teams
Can survive a 1 v 5
You can literately take ults from the entire enemy team
You can catch even the most elusive opponents
Great Ganking
A good amount of damage for being a tank
Can catch and kill every Teemo you come across

Cons:

Early game maybe weak (Depends on how you play and who you're against)
You'll get focused ALOT (not necessarily a con since you're a tank)
Little Magic Resist

This build has multiple uses for your team. The first, and most obvious, is the Tank role. Diving into the middle of the enemy team with your Q ability and snagging the Adc while taking a massive amount of damage is a must. That is unless their whole team is made up of Adc or casters, in that case take your pick.

The second way is to use Volibear as a Support Tank. Just like above Dive in with Q and after you flip your target use your E to fear the whole group allowing the rest of your team to pick them off safely.