I've found Scott Synder is really hit or miss in terms of quality. I'd like to say he's done more hits than misses, but with the prominence of Batman Who Laughs lately, it really shows off his faults.
I think the issue really comes from trying to make the dark multiverse such a big deal. I think it's a great resource for "what if" style stories and I've generally enjoyed the one-shots that explored those worlds, but at the end of the day, those characters/stories amount to "it's the same character you know, but with an evil gimmick." And for one shots/what ifs, it's okay to go with that style of storytelling, but if you're trying to tell a grand epic or a series of overarching stories with those characters, it falls flat.
Like Detrogen said, BWL has almost no traits of either character he's supposed to embody. Even the Batman "I'm prepared for everything" isn't really used particularly well. His plans tend to be pretty basic. It's not like we had a lack of intelligent Batman villains who rely on plans/tactics to beat Batman.
I think Synder just needs to take a step back. He clearly enjoys telling "big" comic stories, but he keeps trying to one up himself over and over again without taking time to really plan what he wants to do. On paper, his ideas could work, but they need to be fleshed out and the reader needs more time for them to sink in. If he keeps trying to do bigger and better things, they stop being monumental events and just become average and lose all their punch. What's worse, is these grand events also tend to have a lot of hype attached to them, so if something falls flat, it stands out a lot more than a lower stakes story.
