[Spoiler (click to open)]While the trailer gives a good idea of what the plot is going for, but I was quickly intrigued to find out not only is the villain Shang-Chi's father, Wenwu, but he's got a damn good reason for doing what he does. At least for about the last ~30 years of his 1000+ year life.
We get Wenwu's backstory mostly told by others, but the short version is he has his own world-wide army of assassins, which has been referenced previously in the MCU all the way back in the first Iron Man movie. His early history is told at the beginning of the story by Shang-Chi's mother, who tells him his father was a power-hungry warrior who got the Ten Rings about 1000 years ago in an unknown manner. He was running out of regimes to overthrow when he went on a quest to find the village of Ta Lo, which is said to be home to mythical beasts, but is stopped by its guardian, Ying Li. She bests him in a battle that's better described as a dance, they fall in love, and he sets aside the rings.
Fast forward to the present-day, and the adult Shang-Chi has been living in San Francisco under the name "Shaun", valeting cars alongside his friend, Katy, who doesn't know about his past. They're attacked on a bus by members of the Ten Rings, Shang-Chi kicks literal ass, Katy kicks metaphorical ass, and we're on our way to the main plot.
I've heard many people complain that Marvel movies are too much the same, which is true, but within the framework, they can cover multiple genres. This one is basically a Wuxia film on a Marvel skeleton, and also manages to touch on modern Asian diaspora issues you normally wouldn't see in a film just because it's rare to have this many Asians in one film. It also manages to tackle some of Marvel's mishandling of Asians in the past, such as when Killian hired Trevor Slattery to portray the fictional leader of the Ten Rings, which kinda pissed off the real one. It was delightful to see Ben Kingsley back in the role, getting a level of redemption you'd never expect for this sort of character.
It's unusual to not have a romantic love story for the lead. While I love that Shang-Chi and Katy are long-term friends and it seems to just stay on that level, it could be read as making the Asian male lead "sexless" which is unfortunately pretty common. There are a couple of moments where it could be read as the potential for actual romance, though reading interviews, the actors say it's just friends for now.
Being part of the MCU means lots of little cameos and the like. I'm curious to see where things go from here, as it's implied that Shang-Chi and Katy are now involved in Agengers business, and we don't yet have the story of the actual Ten Rings. How did Wenwu get them? That alone could be the backbone of another movie, which I think is exactly why they didn't try to detail things here. At the end we learn that the rings are now sending a signal of some sort, and the where and the who is sure to be addressed in a future film, but when and which one remains to be seen. TPTB might not have any idea yet, or only a vague one. I recall Thanos was dropped in at the end of the first Avengers movie, but they didn't really plan on him becoming the ongoing villain until later.