Comment on the playstyle Phantom Dancer encourages on ADCs.
I seriously think that unless you're graves, Phantom Dancer forces ADCs to play like near melee champs. Only maybe Kindred, Graves and Vayne would position themselves closer than their max AA range, and closer than 500 units.
It kinda says "Either you're a melee champ or you've been positioned terribly, so here's free movement speed."
So it's more of a clutch to fall back on if you fail to position, and it's not really something you can make cool moves with, but at the same time it's not something that's a very unique solution (e.g. Zhonya's is the only item that can dodge Karthus's ult, next to Banshee's. You can't really buy a replacement elsewhere.), as it's entirely possible to just buy more movement speed from other items.
I think the passive would be better on an assassin item that gives AD and armour penetration.