Kalista is a terrible character design and very weak champ
I'm talking about the champ as an individual and what she's able to accomplish herself alone. Her power level in the league etc...
Passive - Nearly worthless vs nearly every champ in the game - anyone with a speed burst, dash, leap, hook or any hard CC can make this passive worthless(99% of champs). The time it takes to watch your auto-attack animation go through and then to do a(VERY SMALL) lunge makes the skill pointless to use(you can just run in a straight line faster most of the time. If you auto attack something you didn't mean to, you screw yourself over while watching your AA animation go off. This passive is just not practical.
Q - Basically works a Nidalee spear. Not a terrible skill but very bland and basic. IMO needs a lower cooldown for the damage it does(or, doesn't).
W Passive - Doesn't work at all unless her allied Oathbound champ is also AUTO-ATTACKING(not including regular skills) the same enemy. How often does this actually occur? Rarely at best. And when it does, it's nothing special.
W Active - Decent concept, works pretty good on Rift, but they can easily be destroyed and become useless by just about any player with a brain.
E - Decent skill IF you can actually land all 4 spears on someone because of your slow auto attacks before you die. Slow is decent. Don't have too much of a problem with this Skill. It's basically Twitchs' E.
R - This skill is the most interesting by far and also by far the most useful. The problem I have with it is that it doesn't do any actual damage. It's amazing for saving people or if you really have to perform an engage(ADC performing an engage?).
All in all, I don't see what makes Kalista an 'ADC'. IMO she's not an anything. She lacks a steroid boost for auto-attacks(on the same level as Ashe). I've tried several builds(ADC, AD Caster, Bruiser, Tank etc) and I find she works best when played as a Bruiser with damage. Even then, she lacks so much compared to other champs. Playing her as ADC is like playing Twitch and Ashe combined, except worse than both somehow. There's just no potential in her. She doesn't have the damage to carry the team(because of how her skills work mostly), so that leaves her as sort of a utility support champ with a bit of damage. I paid 7800 for this BITCH and it wasn't worth it(considering a refund, even though I know I shouldn't). So yeah, fuck this champ.
Also, don't give me that "she's new", "you just don't know how to build/play her" crap. I know how to play every champ in this game and have no problems like this.

+
and she can kite them all.