Hey man, I've read through some of your posts and I have a few thoughts for you. I really like the new Kassadin, I think he's in a much better place. A lot of what the other posters have said is true, laning against someone like Zed is going to be a skill-matchup. While Zed might have a few advantages over Kassadin, Kassadin is much more useful to your team and is consistently a much higher threat than Zed.
Zed's kill combo is very simple to counter and once he's blown his R, his level of threat has greatly diminished for a good deal of time. Kassadin on the other hand is a constant threat. He is probably one of the safest assassins in the game right now, especially if he can make it to level 16 with enough farm. He has about 2 seconds to blink in and burst a squishy and then blink out. Other assassins can do something similar, but pay the price upfront. Kassadin can keep doing it over and over again because of the way his W synergizes with his R. Not only that, but he's an assassin that possesses a shield, a slow and his mobility does not dependent on a reset.
I would encourage you to just watch some of the high level of play games on the LoL Client or in the LCS, or even YouTube. Get a feel for how different players approach the laning phase. I've started playing Kassadin and I've found that he is a pretty self-sufficient laner as long as you aren't taking free harass and you are able to harass the enemy enough yourself. Once the laning phase breaks look to roam or even split push. While you are probably more helpful in team fights than other assassins, Kassadin can pressure lanes and objectives very well because he is so mobile and bursty.
