Experience Playing Vayne
I personally have played the champion Vayne in 2 Legend of the Poro King games. Both of these were victories. Thus, I am clearly an expert on the champion.
Advantages to Picking Vayne
Vayne is a tank shredding adc that works very well in the current meta. She is a very strong pick in challenger and professional play.
Vayne is countered by any decent bot lane, but especially countered by Annie LeBlanc bot lane. Understand that Vayne is short ranged and loses almost any trade regardless of the enemy bot lane.
As a Vayne player, be thankful you have someone willing to support you through your bad decision. Take any support you can get.
Tips and Tricks
If you feel like disobeying everything you have learned and decide to play Vayne, don't build Triforce and don't play Vayne in a solo lane. Especially if the enemy has a Fizz and a Rengar. That just would be an awful idea.