Ezreal remains a fairly popular ADC despite the fact that he hasn't been performing well for quite some time (AD Ezreal, at least).
Ezreal has a few unique problems in the live version of the game in terms of game health and gameplay. He is skillshot oriented, so he theoretically should reward players who can aim well and accurately predict enemy player movement. In live versions of the game, if Ezreal does poorly in a game, he can expect to be useless for the rest of the game. If he does average, he can expect to be fairly strong through the midgame, then fall off. And if he does well in the early game, he can expect to do very well through the midgame, and fall off if he can't end the game.
So Ezreal is a champion made for the midgame. His early game is average at best, and often involves farming under turret to stay relevant. So he has to work fairly hard to be strong in the midgame (and falls off either way). He is one of the safest ADCs, but one of the more annoying ADCs to play against if fed (because his abilities are spammable, and he is difficult to catch).
There are numerous problems about Ezreal that could be addressed (in the live version of the game):
* His early game mana is quite difficult to manage
* He is a major annoyance if ahead due to skillshot spam and mobility
* He has very weak wave clear compared to other ADCs throughout the game, despite sharing this feature solely with ADCs who scale very well into the late game
* Despite being branded as a skill based champion, he does not reward champion mastery compared to most other champions
* The mana cost of his W outweighs its usefulness (and as such, Ezreal players consistently win more often when they don't take a single point in W until level 13)
* His passive is outdated when compared to modern ADCs
* He has difficulty securing kills
Looking at the PBE, Ezreal in specific has received one significant change: he can spam abilities more often.
What I would have liked to have seen would have been new utility in his W, reduced mana cost on his early game E (which is so high it practically punishes you for using it), an updated passive, better justification for his poor early game wave clear, or new interactions in his kit that set him apart as a truly skill based champion. Right now it seems that the only things we can expect are Ezreal to be stronger overall because of items and global ADC changes, and more spam oriented, due to the Ezreal specific changes. I'm not particularly fond of this design choice, and I believe Ezreal's kit has issues that could be addressed in a way that is much healthier to the state of the game overall.