The more I think on it, the more I feel like they're definitely doing more telling than showing with Kang.
We know Kang is a threat because they told us he was a threat and they're building all of Phase Five around him, but if you're somebody who doesn't follow every MCU project and you saw this you wouldn't feel it aside from the mid-credits scene. In this movie he just feels like every other weak ass MCU villain, just slightly more menacing due to Jonathan Majors' performance. It doesn't help that this is literally a small-scale threat, so it doesn't sell you on how evil he's really supposed to be, and this version of Kang gets taken out relatively anticlimatically, so what exactly is the sell for him going forward? All these multiversal variants get washed by the end of the movie, but there's a lot of them? That's pretty lame and doesn't really make you buy into the multiversal threat.
It also really struggles with both the threat of Kang and the relative goofiness of the Ant-Man movies. Every bit of the M.O.D.O.K. shyt was horrible, and Darren's sacrifice at the end completely undercuts the tension in the final battle. You also feel it missing the supporting cast of the first two movies.
This was the wrong movie to have MCU Kang make his film debut, but they're in a weird place where they have nobody else--Iron Man is dead. Captain America is
. Hulk is locked into weird rights issues. Thor just have a movie. Guardians is done. Spider-Man has been soft-rebooted. All the Disney+ characters aren't established enough for this debut. Where else could Kang have appeared? Shang-Chi 2? Eternals 2?
Makes me think they spent way too much time meandering in Phase Four to really make Kang feel like a threat in Phase Five.