I liked it, but yes, it could have been much better.
...Each to their own, I guess.
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Now that a few days have gone by and I had some time to digest the experience properly, I can say that unequivocally it's still a bad, bad movie. There's just so many things wrong with it, I can't believe Warner didn't pull it and reshoot the entire thing. In my personal scale, I'd rate this around 2.0~2.5/10, less than equally abysmal X-Men: Apocalypse.
...The best part of the movie for me was the purple car Joker drove. It looked kinda cool. Too bad it's now at the bottom of the river...
It's symptomatic of the entire DC Extended Universe - there's no apparent planning beyond the next film in the series.All show and no go, just like the movie pretty much.