Hey hey!
I just tried Vi and wow... she's amazing! You did an amazing job, she's SO fun to play, like seriously. For your first champion, you went beyond my expectations. It just feels so satisfying punching everything, it just feels 'right'.
Q:
I think her Q is really unique and fun to use. It just feels so cool skidding across the floor to your target, and it's a skillshot so that makes it super fun. The only thing I don't like about it is that when you press Q, there's a very very tiny delay and you stop for a second and I don't know if that's intentional but it makes it feel a little clunky. When you get cc'd though, it acts kind of weird. When I got snared I had the Q still active but it was on cooldown so I couldn't auto attack and I couldn't do the dash either.
W:
Her W is super duper strong, so satisfying on the third hit.
E:
Really fun to use as well, I love how it has an 'ammo' system and it isn't just one cooldown.
R:
Oh my goodness this is so fun to use, I think it nails her kit in place, it just feels 'right'.
Style:
I think her style's great, I love the colours, I love her eager personality and everything. Her voice is good, I LOVE her sound effects. The only thing I don't really like is her hair but that's fine.
She feels like a combo-fighter, like Riven but even though they're similar they also feel really different so that's really well done.
Overall I really love her, you guys did an amazing job.