Hey, I'm Chaz19 (Also known as "GetRektGGEzLife", but my current account is "Blame Yo Jungler") from EUW and Vi is one of my most played junglers. Vi can be played as an AD Bruiser, or an AD Offtank. Some people play Vi as full tank but it's really much better to go Offtank since Vi has strong damage with only a few items. She has the ability to do a strong level 3 gank and is decent at duelling due to her W and her passive shield. Mid game is where Vi excels when she has her ult, she can completely begin turning the game into her favour. Late game Vi is a beast since she is tanky as hell and also does a ton of damage and shreds tanks due to her W.
Pros / Cons
Strong at all stages of the game
Her ult is definitely one of the stongest and can completely take a carry out of a fight
Can be built bruiser or offtank and still be successful
Has a gap closer
Good at duelling
Has %max health damage and armour shred to deal with pesky tanks
If you don't land your Q, the gank is often unsuccessful
Your Q slows you down
Invulnerability cancels your ult and cooldown isn't refunded
All AD damage - easy for enemy team to itemize against
Vi is a strong jungler at the moment as she smashes tanks to pieces whilst being tanky herelf and is also very fun! Enjoy!