The "Secret Invasion" comics event revolved around a Skrull invasion of Earth with the shape-shifting aliens playing the long game by infiltrating and replacing well known characters within the Marvel universe. There was a lot of build up as the heroes and readers had to ask themselves who they could trust. With the MCU series of the same name, it's scaled back to a Nick Fury centered series as he works to prevent Skrulls from taking control of the planet, going for a sci-fi inspired spy thriller. When all is said and done, the series will leave you wishing it had gone bigger.
I don't think "Secret Invasion" has the impact it was going for in-universe and out. The only teases we had for the series came in "Spider-Man: Far From Home" and "WandaVision" and only two established MCU characters were revealed to have been replaced by Skrulls. This doesn't exactly evoke the level of excitement or paranoia a story with such a premise should deliver, not to mention it glosses over the implications of the characters that were supplanted. This is probably why "Secret Invasion" isn't getting people talking compared to the other Disney+ Marvel series. In fact, it harkens back to the pre-Disney+ Marvel shows, feeling like it's an offshoot of the main MCU narrative rather than a part of it, especially the parts where Fury refuses to get the Avengers involved.
It certainly makes me wish that maybe Marvel should have built up a Secret Invasion movie before moving on to Kang. Imagine a few years of our heroes wondering if someone they've worked with may be an imposter. They could have shown Skrulls taking major positions in Wakanda, New Asgard or Kamar-Taj. And it all could have culminated in a battle between the Avengers and Super Skrulls (but not like the uber ones we got in the climax of this series).
I will say that the shows does succeed in a few areas. For one, it plays well with the post-Endgame landscape, with the effects of the Blip pushing the Skrulls to act more villainous like their comic counterparts after being shown as victims in "Captain Marvel". Unfortunately, the way they go about it isn't exactly original, with the villain plot being a combination of those from "X-Men: First Class" and "Peacemaker". The main villain Gravik is also like Koba from "Dawn of the Planet of the Apes", only with a less satisfying defeat.
At the very least, the series is well acted, with Samuel L. Jackson really shining as Nick Fury. Rather than directing the heroes to where they need to go, we get to see Fury take the lead, allowing Jackson to really cut loose in the role. We also get to see Fury in a more vulnerable light, as he reflects on his past failures and is another character suffering PTSD from the Blip. Some of the best moments also come from his shared scenes with Ben Mendelsohn, Don Cheadle, and Charlayne Woodard.
Despite some good ideas and acting, all I really see with "Secret Invasion" is wasted potential. It's hard to say whether events of the series will be important as we move further into the MCU, but right now, this feels skippable.
