I am a Jhin main, and I must say that Jhin is a very good adc, but is not broken skill-less cancer analogous to
etc, provided that your opponents know what they are doing; he is balanced but is on the strong end of the spectrum atm. I managed to get bronze 3 despite smurphs, bad matchmaking and autofill supports who never ult, so I'm probably somewhere between B2 and S4 in skill, and even at this low elo I can see this is the case. If you and your team don't exploit his weaknesses then he will seem broken, because his strengths are stronger then they are on other adcs; but it doesn't mean he's actually freelo/unhealthy for the game.
Jhin has extremely significant and defined strengths and weaknesses.
--Passive. Lots of damage but can't fight back if initiated upon while reloading. Also gives him more burst but far less dps then the enemy adc in teamfights. If you push you can make him waste his shots counter-pushing.
-Q. Far less damage then the enemy adc's Q unless they stand by two or more low health minions so you can bounce it from minions, killing those minions, and onto them. Also low range.
--W. Can be dodged by decent players in many cases and has a LONG cooldown. It's very good, very, but other champs have cc that's as impactuful.
E. Good to slow down flanking etc. Can also be used in fights but isn't as effective. His W and E are not enough to stop flankers or divers such as
etc from killing you; you must rely on your team for that as you also lack mobility.
R. Quite strong but can be dodged. Especially with flash or movement abilities. Hitting a good player with every shot isn't always easy. There's a range, about in the middle of it, where it's very difficult to avoid, but this can be played around often. Also can be stopped by cc, or by getting flanked. It doesn't do much damage if the enemy isn't low health, meaning if you use it for pics, you are giving up a lot of damage in exchange for utility. Other adcs have ults that kill you while you try to escape; but they are easier to use.

are also adcs that are quite strong in the right hands, despite not having a very high skill floor, and are staples of pro and high elo play. That doesn't mean they are total freelo or unhealthy.
There are other ADCs that are more oppressive in lane if the person playing them is good and uses them to their potential, like
with absolutely insane damage poke, great all ins, AOE cc that sets up their support for an easy Q, and press R kill the enemy adc and support who are at 30% health, and
who can just abuse her range to poke you so much, while stopping you from getting close with traps, and hitting you for 1/4 or 1/3rd hp with her Q the moment you take your eye off her and don't see the Q animation or get CCd.