Bearing that in mind, I can describe Ant-Man as a great adventure movie that is a lot of fun to watch despite its troubled production history...but it doesn't have a whole lot to say.
And that's okay, it doesn't need to have a lot to say. Its primary purpose is to entertain, and it does that in spades. Paul Rudd has a ton of charm and is very convincing as Scott Lang, a reluctant thief who ends up involved in a scheme to keep Hank Pym's (Michael Douglas) shrinking technology out of the wrong hands. Evangeline Lilly plays Hope, Pym's estranged daughter, whose emotional distance from her father hasn't prevented her from embracing his principles.
Additional support comes from Lang's roommate, Luis, played by Michael Pena, who not only brings great humour to the scenes he is in, but gives director Peyton Reed an opportunity to depict some of the story's exposition in a very entertaining way.
The real star of the movie though, is the visual effects. Depicting the adventures and terrors of humans shrunken to a tiny size has been a Hollywood staple since its earliest days, but has been largely absent since Honey I Shrunk the Kids back in 1989.
Like that film, Ant-Man's best moments come from watching him negotiate a familiar world from a vastly different perspective, as Scott Lang, reduced to perhaps a quarter-inch in size and unsure of his abilities, avoids being washed out or drowned in his own bathtub, only to end up clinging to the grooves of a spinning record, and then having the negotiate a jungle of crushing feet on the dance floor.
The shrinking effect itself is pretty much a strobe, similar to how it is depicted in the comics, but the rapid (and occasionally panicked) transitions are well handled, especially in the fight scenes. Likewise, the interactions with the various species of ants that Pym's technology allows communication with are imaginative and well handled.
If the film has a weak spot though, it is probably the villain. Tom Hiddleston (Loki) once said that Marvel's genius, both in comics and in their films, is that they make their heroes flawed, and their villains heroic. It's not like everyone wants the Red Skull in their wedding party, but none of the villains in the first phase of the Marvel movies were straight up megalomaniacs bent on world domination for its own sake, and they often have some redeeming characteristics, or at least a relatable motivation.
Pym's former protege, Darren Cross is just another smug corporate bigwig, passive-aggressively trolling his old boss as he tries to replicate the shrinking tech the Pym now conceals out of fear over how it might be misused. Despite being an able scientist, Cross displays very little in the way of smarts, and even though he is by implication a solid businessman, you are never given any insight as to how.
Corey Stoll does a decent job, given what he has to work with, but the best opportunity to make him even the least bit sympathetic, the referenced but never depicted falling out, is squandered. When you consider how well this worked in humanizing the villain Syndrome in The Incredibles, it feels like a rare mis-step for Marvel's Kevin Feige and company. By the time Cross becomes Yellowjacket, he is just another cardboard villain, which is a bit of a shame. As a result of this, the picture's theme, such as it is, has to focus on redemption and the reconciliation of two men separated from their daughters.
On the plus side, in an adventure-comedy-heist picture, a villain is practically superfluous anyhow, the real menace is the Ticking Clock, or Consequences of Being Caught, or, in this case, Failed Redemption, and Ant-Man plays the angles very well on these other three elements. It may also be the most accessible Marvel film in a while, being well paced, extremely funny, and requiring no interstellar world-building or convoluted backstory. There is a joyful 80s vibe running through this film, and despite his having departed the project, original director Edgar Wright's fingerprints are still visible throughout it.
Everyone is waiting for Marvel to stumble, but Ant-Man is a good, if basic film, with solid but simple ties to the Marvel Cinematic Universe. As the last film of Phase Two, Marvel's True Believers can rest easy; despite having to take liberties with the source material, Marvel has kept the faith and not only made a solid adventure film, but have also left the door open for Scott Lang's participation in the wider MCU. In that tradition, if you are a fan, you will probably want to stay until the very end of the credits.