I've played every champ except Ahri and Varus and I've got to say that out of the box Zed is the most difficult to play, at least for me. But I'm picking him up a bit. Overall though I'm leaning towards agreeing with the original poster that he is a bit too squishy. His damage is not really overwhelming like leblanc or diana. Other champs like wukong and Jayce seem to do just as much damage yet are twice as tough and have better escape methods and utility. Yeah he can use his W to escape, but chances are it will be on CD when you REALLY need it to make an escape, since he also depends on it for damage during a fight.
Dont get me wrong I reallllly like zed and think his overall concept is awesome, but they need to give him more survivability. One suggestion is instead of giving him more HP make it so enemies see his shadow as a clone. That would add a little confusion and reduce his probability of taking damage. I mean Wukong has this skill, PLUS he goes stealthed, AND he is considerably more tanky then Zed. Maybe to soften this idea so its NOT OP is to make the clone untargetable. I dunno just an idea. But Zed really needs SOMETHING. His W is just to weak an escape, especially when compared to other champs.