I bought DOOM Eternal a couple days ago for half price (I never buy games on release day for this very reason). It's even better than DOOM 2016. The enemy encounters feel more natural because they don't require activating gore nests; although, they still occur in set locations. The music is still amazing, especially the battle music, but it does seem a little repetitive.
Maybe this is just the old man in me, but I do think there's a little too much going on in terms of upgrades and tokens (not sure what to call them): There are crystals that give you a perk and also more ammo, armor, or health; tokens that give you new suit abilities (found in the levels), weapon modification kiosks (found in the levels), a tokens for upgrading the weapon upgrades (earned through combat, I think?). I think some can be either found or earned. Additionally, there are batteries around the levels that unlock areas in the hub world, leading to more tokens, etc. It's just a lot to keep track of, and it seems needlessly complicated for an FPS. Doom 2016 had a similar system, but I think there were only three types of tokens.
Another old man issue I'm having is how many buttons I have to remember - LCtrl/middle click: grenade, G: switch grenade type, F: switch weapon mod, E/mouse thumb: melee, R: Fire belch, Shift: air dash, C: chainsaw. I keep getting confused in heated combat about which key to press or accidentally hitting something in a panic. Also, lots of ways to switch weapons: Q, number row, mouse wheel. All of these are accompanied by icons on the HUD that I'm supposed to use to keep track of recharge times, which goes out the window during combat.
It's also funny that some of the levels basically look like Bowser's Castles with the fireballs and rotating fire ropes.
All that said, my only actual complaint is how linear the game feels. The level design does create some interesting arenas for combat, but I never feel lost the way I did in the old Doom games.
I have yet to try out the multiplayer. I'm one of the few people who actually enjoyed Doom 2016's multiplayer, so I'm hoping this is just an improvement on that.