I've not seen the new cut of Justice League yet. I will give it a watch at some point. However, I do agree the original cut was an incoherent, indifferent mess.
I must confess I'm not a fan of Snyder. 300 is probably the only film of his I've sort-of enjoyed, and I really dislike his take on the Superman character. Man of Steel had some good snippets in the opening half, particularly Kevin Costner as Jonathan Kent. But the way Snyder killed off Jonathan Kent in a because-we-can tornado sequence was ludicrous, given that Clark could easily have saved him. It's a far cry from the subtle poignancy of the 1978 Superman, where Clark really could do nothing to prevent his adopted father's sudden heart attack.
As for the second half of the film, there really is only so many times you can throw General Zod through a skyscraper before it just becomes numbing. Normally I like Michael Shannon, but give me Terence Stamp's take over his any day ("Why do you say this to me, when you know I will kill you for it?"). 1980's Superman II has flaws, but it is a damn sight more fun. More importantly, both Superman and Superman II don't make the idiotic mistake of trying to make Superman "dark". The noble, heroic character is beautifully contrasted with his Clark Kent bumbling reporter alter-ego, played so brilliantly and definitively by Christopher Reeve. Then of course, we have the sparkling, comedic chemistry between Reeve and Margot Kidder's equally definitive Lois Lane.
Again, I've nothing against Henry Cavill or Amy Adams, but they were given very little to work with, and Snyder's humourless take on their relationship has zero romantic chemistry. This is doubly true of the Batman v Superman debacle, which stood in stark contrast to Marvel's excellent Captain America: Civil War - a superhero film that actually followed through (superbly) on a similar premise.
All that said, yes I will watch this new cut of Justice League with an open mind, hoping that Synder delivers the goods, despite my disdain for much of his other work.