Honestly, I'm leaning towards loving (well, loving to hate) Eisenberg's Luthor. Is it comic Luthor? Absolutely not. Can I understand why people hate him? Absolutely. Ultimately, I think it's the same type of situation as D'onofrio's Kingpin. Some people hate the little idiosyncrasies that they bring to the role and that's totally understandable. Kingpin, for instance, had the benefit of looking a lot like his comic book counterpart, but he really did seem to have like a form of asperger's or something, which I thought was fascinating, but some people really just despised.
This seems to be kind of an interesting trend, in terms of the big villains. Zod was a zealot and a supremacist, but you understood his motivations, and, even though he was a man hellbent on committing genocide at a global level, he was, ultimately, trying to ensure the survival of his race. I'm noticing with Suicide Squad and BvS, though, we're seeing the dawn of the repugnant villain. Luthor kind of put me in the mind of Grima Wormtongue in that he's this sniveling petulant little ****.
Only, he's worse, because he also has that superiority complex and he's a Machiavellian manipulator who does despicable **** to further his own plans. Leto's Joker seems to be a similar beast, not only from all of his ridiculous on-set antics, but, also, just from what we've seen of him in set photos and on screen (beating Harley, pissing on her, from what DiFabio said, basically treating her like a whore), not to mention the visual indicators, which basically paint him as a ********* who bought into his own hype.
In all honesty, it's kind of easy to see how our heroes could be darker reflections of themselves, when the people they go toe to toe with are such disgusting monsters. It also kind of adds context to the idea of Justice League being a lighter film, because Darkseid's motivations, assuming he's the villain, aren't as personal; there's a purity to them. It's arguably darker than Joker or Luthor or anyone, at a grander level, but the key is that it is at such a grand level. Battling for the fate of the world or the universe or the cosmos or whatever is fundamentally less ugly because you aren't really focusing on the people.
When you're down on the ground, though, and watching Luthor threaten to immolate Ma Kent unless Superman does his bidding, it's abhorrent, but I feel like it really works, because, for as long as I can remember, in DC movies, and, specifically, in Batman movies, there's been a trend of the hero being outshone by his adversaries. They've always worked as a sort of showcase for the bad guys, and now we're living in an age where you want to hate them, and you want to see Batman brand Luthor's head.