I would say myself that while I remember enjoying the movie back when I watched it with friends, it surely wasn't something to remember after that, and I even remember having to check Wikipedia's synopsis back when I was trying to write a review on this movie (which I was still charitable with the funny moments and I guess trying to make Shazam really look dead until dropping WW's magic touch).
It is arguably straight in the middle of the road: Not absurdly terrible unless you are used to way better things/analyzed the story enough to find the cracks...but also not great enough to be worth talking about other than a passing mention and few things that you might have liked about the movie. And you know, even if "mediocre" isn't as bad as "bad" in some cases, not standing out in either way is what can get some movies completely buried with time as anytihng that isn't super good to stay relevant later...or bad enough to be discussed about why it is so bad (often because of entering the "so bad its good" realm).
No idea what to expect about Flashpoint since I'm not a DC fan and hadn't watched any other Flash movies, but heard from a friend that James Gunn is going to be at charge of the new Superman movie after that reboot, so I will be intrigued to wait for that after having watched (and really enjoyed) Guardians of the Galaxy Vol. 3.