Oh my god, this game is fantastic and I love it. Mechanically, it is much more cohesive than Doom 2016 in my opinion, and I think it comes together to make the firefight loop into something that matches my (fairly agressive) playstyle. Also, it's a 3d platformer now, you get a grappling hook, you climb walls, it's wild. These two things in concert with each other makes the game so much more kinetic than 2016 ever was for me
Now, I was vaguely aware that there was lore of some kind present in Doom 2016, but didn't really pay attention, and never read a single codex entry. Just wasn't what I was there for, so their decision to make this lore extremely present in Eternal meant I spent the first few hours of the game being just a bit confused
I still didn't read any of the codex entries, but, by the end of the game, I had a pretty solid idea of the setting, and really enjoyed the experience of having my understanding expanded like that. Turns out there's a bit more going on than "Man Literally Too Angry To Die takes it out on Hell".
Of course, this expanded lore isn't gonna be for everyone, which is likely why it took such a backseat in Doom 2016