It's interesting to note that DC's Atom first appeared in October 1961, and Marvel's Ant-Man January of 1962, which shows, I think, that much like movie studios, comic book companies are more about the "me-too" than being original. I always liked The Atom, while Ant-Man would be the sort of thing that (as a kid) I would point to as dumb.
The two are virtually interchangeable in terms of powers, except Ant-Man can command the mighty power of ants. Which is especially dumb, but in that classic comic way of "Gentlemen, we've conquered the problem of ant communication and control and, oh, by-the-way also figured out how to decrease the size and alter the density of arbitrary objects."
No connection between the two, but the same scientist is always good at doing All The Things.
Where the concept is not dumb is that shrinking things down and seeing ordinary items at a ginormous scale is cool for bored comic book artists. This sort of thing is usually disastrous in cinema, resulting in the bulk of Bert I. Gordon's (Beginning of the End, Village of the Giants) oeuvre.
It's so dodgy cinematically, because of composition issues completely destroying the suspension of disbelief, that it can induce eye rolling in a good film, and stand out as a particularly bad element of a bad film—like the little French dudes in Willow. (Remember them?)
Add to this the fact that the mastermind behind this as a movie project was no less than Edgar Wright (the Cornetto trilogy), and he dropped out mid-production due to "creative differences", mixed in with unencouraging trailers—well, we were very cool on the prospect of seeing it.
And yet! It's good! And it's kind of nice that, even though the world is at risk (because it has to be, right?), the movie by-and-large has an intimate feel. It is, essentially, a caper flick—something the villain actually notes toward the end.
And departure or no, the film is still full of Wright-goodness, such as Ant-Man's gang-that-couldn't-shoot-straight pals, especially Michael Peña's can't-get-to-the-point gunsel.
But really, this movie was going to rise and fall—however good the script—on how the shrinking was done. Done poorly, even the best script wouldn't have survived. This movie uses a mix of macro photography (like Microcosmos) on the one hand, but on the other does a lot of gags where our hero shrinks down and immediately grows back. (This is his primary fighting style, in fact.)
In essence, they normalize it. Almost every other shrink/grow film I can think of spends inordinate time on the gee-whiz factor of it all. "Look how small/big I am!" This hurts because, typically, the effects are cheesy to begin with: Back in the day, Universal Studios had a giant hand (and maybe pencil) so you could have your picture taken "tiny sized", and that wasn't much worse than what they used in their movies. But it also hurts because nothing happens while you're gazing around in wonder. (And you can't really do much without ruining the shot, at least pre-CGI.)
Here, the small stuff is all done in montage, and in action scenes. It was a wise choice. As was switching from Ant-Man's perspective to a more normal one, for comedic value.
Fine cast. Paul Rudd handles it easily. Bobby Cannavale plays new boyfriend to ex-wife Judy Greer. Some amazing CGI done to make Michael Douglas look 30 years younger. Evangeline Lily is the new love interest. I particularly liked Corey Stoll as the villain. It's kind of a hack role—the apprentice to Douglas' mad scientist who turns evil—but he really nails it, brings some nuance, and gets that love-to-hate thing that makes for a good baddie.
The Boy, who was particularly reticent to see it, liked it a lot, commenting on the modest scale. (The shortest of all Marvel Cinematic Universe Movies, they tell me, it's just short of 2 hours.)
I still might seek out the original script to see what Wright had in mind, but Peyton Reed (Yes Man) did not fumble here.