is ekko kit balanced / overloaded ?

So now that its been a few days that ekko's been out I'm questionning, is hit kit blanced / overloaded ? I played both as and vs ekko. and I must admit, personnally I find him to have to much in his kit or a bit in need of balance. http://leagueoflegends.wikia.com/wiki/Ekko considering his mobility, damage and cooldown, the only things that kinda bug me are those: 1- I'm questionning the need for him to have shield on his w, does he really need it as it already offers a slow, vision, and potential aoe stun ? his w already offers him execute damage so... is the shield really needed i mean its a 330 shield at lvl 5 + 80% ap, that is a lot no ? 2- his ult has no mana cost. for all the utility it offers, is it normal ? I mean its a repositionning tool, heal, and aoe nuke. 3- the ap ratio on his ult. yes I understand it can be hard to use offensively and the ''hologram'' makes it partially predictable, however, 1.3 ap ration on a skill whit such utility, is it really needed considering his kit already offers decent ammount of damage and mobility ?

personally, I'd change his ult a bit to make him feel more like an assasin then he already his, ex: give his next 3 auto attack a damage boost after activation of his ult and apply an aoe slow ( no damage ) where he lands instead of an aoe nuke.

what do you guys think ? is he fine the way he is or do you think he packs a bit too much ?