Most of his stuff looks like it could be balanced, but what looks broken is the potential for guarenteed crit chance and wind wall.
Wind Wall can block some friggin ults, and it's just a normal skill. That shit could seriously bone most mid laners.
Grab some Brawler's Gloves and crit runes and you have a ton of crits first hand in the game. Grab an Infinity Edge and raise your crit % chance to 50%, then you'll already have 100% crit chance with crit damage bonuses to top it off. Not to mention the potential of crit damage runes- look, that just seems overwhelming.
Balance issues aside, he looks pretty damn awesome, both play-wise and lore-wise. Once I get a proper mouse/laptop to use back I'll be nabbing him, quick.