I like Zed, a lot. He's definitely not one of the easier champs to play.
One person stated earlier that we'd see how he is after people stop maxing Q first. My response to that is, why? What are you going to max first? E? Then you have no poke (or no useful poke). Your Q and E are going to do nearly the same amount of damage, the question is, do you want to poke for it or do you want to be face to face? The only time you should becoming face to face with people is when you plan on killing them, which you're going to be launching both your Q and E.
Yes, the E has a shorter CD, but again, read the previous paragraph.
Your W is not meant to be used as a gap closer, unless you can kill the champion escaping in one hit. It's used to set up positioning around your enemy to land your skills twice.
Use W to set up a crossfire for your Q.
Use W right on top of you to land an easier Q.
Use W on the other side of your enemy when your enemy dives you to land E/Q combo, slowing them. While running away from your shadow, if you can win the fight, fight. If not, you can use W to get back to your shadow, further away from enemy for a safe escape.
Use W to escape over a wall when running for your life.
His burst damage is amazing mid-late game. Usually after you reach level 11. You can ult into team fights, land 2 E's a Q, and use your W to escape while taking very little to no damage. Usually killing the champ you ultied and leaving the surrounded ones low. It is for this reason I like him more than other assassins. He has the power to do a lot of AOE damage. (Dangerous, but amazing when done right.)
But, I am in no way saying he is the best. As previous posters have stated, there are other champs that are way easier to play that have better and/or constant damage output without using any skill at all. But Zed is still way more fun.