I agree. Its just able to give you the visual sense of what the Astartes can do. They are not mindless killing machines. They are cold calculating tacticians of war that are beyond super human. GW needs more of this.
I really do appreciate that about this series. Sometimes GW stuff can go over the top with what I like to call the "put a cathedral on top of your tank" aesthetic, which is as described. Lots of screaming, lots of hyper-baroque-gothic adornments on literally everything, people, spaceships, and architecture alike, and just kinda focused on some weird sense of epic scope rather than maintaining proportionality or comprehensibility. Also, most people get the details wrong. Like how bolters are gyrogets with HE heads, so they zoom and then bang when they hit the target.
By comparison, Astartes is much more muted. The gothic elements still exist in the adornments of the Space Marines, and the brief shot in the first episode showed the censer over the bolter to demonstrate the religious rites in a low-key way. I really find that portrayal appealing, and that light touch extends to the combat. Their religious zealotry comes out in their unerring execution and their determination, and that's valuable.
I actually hypothesize that Astartes, from a design standpoint, pays careful attention to the works that GW was inspired by when they first came out with 40k way back when, or perhaps very early editions like the old Rogue Trader rulebook. The space visuals from the second episode, as well as the craft design, hews closer to the cover of a sci-fi book from the 80's and 90's than some of the wilder, more ornate stuff you tend to see from the setting these days. These marines are relatively unadorned and don't do stuff like those mystical prayer seals dripped on with wax. I think this muted tone actually really works in favor of the material.