Well what I'm about to say is just my opinion (and in no way a request for changes, buffs or nerfs) that's mostly generated from me being a Leblanc main since forever (no surprise there from my name) .. First of all I'd like to point out that I've been maining her long long before her rework, which I'm not really inclined to say it's great nor bad for a couple of reasons:
1: I like the new ultimate idea they gave her, yet it's pretty much horribly executed, I like the concept of choosing which ability to use instead of the old one where it only mimics the last ability used, what I don't like is the mirror that she can now "cast" ... Compared to her old passive's mirror, the lack of control on her ultimate's clone is pretty poor and unfitting for a so called "deceiving mage" ... I would have expected at least a degree of controlling it, yet it's controlled by a very poor AI that has a very poor judgment, topped off with a high cooldown for a mirror that can't survive one basic attack hit and disappear the second it casts an ability so hastily, meanwhile other deceiving champions get a clone that's more fun to play with being more useful and has the actual potential to fool enemies a great deal (cough shaco cough)
2: Her passive, yes... The passive is something no doubt fair for her targets (IN LOW LEVELS) to escape in time, BUT in most cases (at late levels) burst her down first, in this situation I cant help but to feel that it's very unfair to LB specially in teamfights, that 1.5 seconds proc is a HUGE disadvantage against most champions to which during that time she is pretty much only able to deal damage with her very low basic attack damage, a champion's passive should be made to their advantage when it's done properly, not disadvantage, we don't see ahri's passive dealing a DoT to her if she misses a Q, or a HoT instead of proc heal simply cause it makes no sense, and ahri is classified closely to LB (kiting mage) a passive that takes 1.5 to work is a very long time and makes no sense for a champion's advantage from that champion's point of view
3: Whether you agree on this with me or not, LB is a very squishy champion, the whole "low risk high reward" thing is not true, LB risks a great chunk of her health in a trade, specially with that W recast timer
Overall LB (in my honest unbiased opinion) needs a rework to a couple of her kit not all of it, something that allows her to be fun to play with again and fair to both the enemy and LB herself, since the rework, I can't help shake the feeling that LB became clunky and weird to outplay with, the many nerfs on her (sadly) now main damaging ability E's missile speed made her easier to furthermore counterplay, and W's extremely low damage is something that I might come to understand eventually since it's now a positioning ability rather than a main damage source
Sorry for the long post, just my thoughts are passionate about LB, she always fascinated me :)
Truly hope they make a fair rework this time