I agree with many others saying that his Q should be slightly larger, to more accurately show the hitbox (if it doesn't currently, tough to tell) and to better fit the size of Piercing Arrow on the original skin. It may only appear to be smaller due to lighter particle effects, but it definitely doesn't look the same size. Overall, however, a great skin that I would purchase if priced at 975 RP.
As another poster mentioned, there is a bug when dealing with his W and multiple minions, switching targets. This also applies to Runaan's Hurricane and Varus. See the video for a larger description. Essentially, the Blighted Quiver applies extra spell effects to one target instead of the intended target. This can happen when just right clicking minions and, as shown, with Runaan's Hurricane. Another poster already did one covering just autoattacking, but I wanted to show it can also happen with the Hurricane item.
Youtube Link: http://www.youtube.com/watch?v=MvzdHYms-Ts
EDIT: This is a visual bug only.