What makes Jhin desirable compared to other ADCs?

Utility Long range Burst damage Executes

has HIGH damage vs any other ADCs in the late game(the only one who can do that much is vayne but she doesn't have the range that jhin does) and he almost becomes a ranged assassin in the late game that can still melt a tank's health bar w/o a problem. Tanks are huge in this meta and jhin/ashe/varus has the DPS to act deal damage in the fights.

The number 4.

He is a good lane bully, can be a little safeish with movespeed, traps, snare. Also i think he is good for people who arent good with other ADCs. He doesny have to be right there with his team (ult and snare) . I mean his ult can be used as an engage from a mile away, thats pretty unique. So if you suck and are geting zone but something happens you can safely help.

Very tilting to kick a Jhins ass out of lane and then gank comes and he gets the worlds safest double kill.

good CC with W which is pretty rare on a non-ulti ability for adc, ult good for utility and good damage for executing. He scales more smoothly with crit as well.

He's actually pretty fun to play, maybe cause he doesn't build the obvious Attack speed stuff and just seems outside the box gameplay.

if he's on free rotation, i would pick him. he's easy to learn, hard to master.

because he's cool unlike the rest of the marksmen

Utility.

raw damage

Jhin is a pretty strong overall champion who fits into multiple kinds of compositions fairly well. All in all Jhin functions as an engage/poke champion who synergizes with his team using his W to make picks from afar so long as the enemy is marked by an ally or opening up with Curtain Call. Through the game his 4th shot deals a ton of burst damage and Jhin's high AD definitely brings that damage to reality.

He is a strong lane bully, can play a lane safely and possesses decent waveclear. His four shot combined with his movement speed steroid. passive enables him to efficiently kite in and out of combat without losing out on DPS.

His weaknesses consist of his lack of mobility, self peel, general squishiness, the fact most of his damage is loaded into his fourth shot in both his ult and basic autos. Lategame most ADC's will easily outduel him straight up simply because of they're damage per second vs Jhin's health. The focus on Jhin's ult can often lead you to being dived on as curtain call reveals Jhin's location at the very start which is in turn highly telegraphed. Jhin's grenade bounce doesn't deal a lot of damage without minions hit prior. Two of Jhin's abilities are skill shots which includes all 4 shots on Curtain Call and his W.

Jhin is one of the most reliable carries when it comes to matchups. - http://www.lolking.net/charts/bottom-matchup?region=all&range=daily&map=sr&queue=1x1&league=ranked speaks for itself.

He's got three forms of CC.

He can adapt to any composition, but flourishes in pick and seige- the most common two.

He is not outranged. Having trouble in lane? Max W. Hit three on the carry. Ult. I'm not sorry.

His weaknesses aren't capatalized on in low elo. You can easily engage him after his fourth shot, but you've run all the way behind your tower to avoid it. If you get him running- he's dead (this also means he -has- to stay and fight, which is why Jhin is so aggressive) It's also impossible for him to chase and attack anyone if his snare is on cooldown- which he needs to hit you for. His CS is also very disruptable. - but people don't often think about outfarming him.

He also gets a lot of assists- which I can't tell whether it's a strength or a weakness. I'm pretty sure Riot accounted for it when he's been balanced- but it can get him a lot of gold so he can snowball with no kills.

(Also I'm a Jhin fangirl, so I can answer that question in two ways -wiggle eyebrows-)