I had the 'pleasure' of seeing this on Wednesday at a preview (non-studio sponsored). So probably one of the rare screenings so far that haven't been slammed with comic fans, midnight night pre-sales/whatnot. Aka very much a slice of general audience.
I don't think this movie is going to play well to the general audience at all. Those are the people who will keep the numbers up on Saturday/Sunday and next weekend.
There were elements that left me utterly confused and I probably had a better grasp of some of the comic elements than 95% of the audience. The dream sequences I had to explain to the group after.
The Flash part even I wasn't sure what was going on, but connected that perhaps it might be the Flash, needless to say no one else managed to get it
My theatre also boo'd after the credits (when there was no post-credit scene). Regardless of the underlying reason, there was booing - at a free movie, which is pretty deserved.
In the desire to not copy the MCU, I think having the JL segment interrupted the flow of the movie was a horrible decision. That would have been a worthy post-credit or at least post-end scene.
Worst part of the whole movie:
The 'your mom's Martha, my Mom's Martha... did we just become best friends? Yuuuuupppp!
In the end, what really sticks with me is that this feels like a 2.5 hour movie that is based on a 10 episode TV show. Way too many plot lines, way too garbled and yet somehow it feels like none of them really resolved and are just dropped. This reminds me of the Last Air Bender's translation to movie. Garbled, non-sensible, most of the characters just are complete misses of the source material. Simultaneously too much going on and yet somehow nothing really happens. Jumping from plot point to plot point only to drop them for a CG battle.
All said, it's still watchable. I think that's why every review seems to be around a 2/4, D etc. Even the positive reviews hover around a 6-7.
A 5/10 is where I'd go. Watchable, but not something I would talk anyone into seeing. At the same time, if you really love comic books and DC I would never try and talk anyone out of seeing it.