Ez doesn't 'feel' powerful by the nature of his skillset (and the repeated nerfs to make none of the skills stand out as amazing). He's not weak, but you must connect with all his spells or he will certainly seem weak. He's not about constant, high damage output (like Twitch) he is about chipping his target down with repeated skillshots until they fall.
If you're looking for a champ that dominates teamfights, Ez will not be to your liking. If you want an amazing harrasser, and good chaser, then you might want to consider it. He's not a 'right click to win' champ like Twitch or Tristana, but a mobile skillshot spamming machine.
Still, it might be better to wait for him to be free to play and decide for yourself. Though that could be a while.