The game really starts to pick up after what it calls the point of no return, because by then it feels as though everything is starting to kick into overdrive. It feels like something is finally happening, which is honestly a problem with most of the game. The final part has urgency where most of the game feels a bit lacking in the tension department. And in the gameplay department, these final areas are without a doubt the best fights in the game. They're tough, but by this point you have the tools to actually fight everything so it feels like a legit challenge. It's fantastic stuff.
The final bosses are also insane. The Khan Makyr boss not so much but it is a visually interesting fight. The Icon of Sin on the other hand is just pure chaos. It's like if they took the initial concept of the boss and cranked that shit up to 11. You got monsters spawning everywhere while the Icon is launching massive attacks while you try and deal damage to him. It's pretty overwhelming actually, and I can't imagine how difficult it's gonna be on UV or Nightmare. I feel sorry for the poor bastards doing Ultra-Nightmare. I always felt the Spider Mastermind was a bit too lacking in either spectacle or excitement. The Icon is seriously one of the most intense boss fights I've ever come across. It's kinda emblematic of the whole game actually.
I really didn't care for the ending though. After you beat the Icon, the Slayer just walks off while narration says his fight is "eternal." And...that's it. There's no denoument following what's possibly one of the most intense boss battles in recent memory. It feels empty. Doom 2016's ending was brief, but was loaded with intrigue like the Slayer getting banished and Hayden revealing the true nature of the Crucible. There's not really anything like that here and it feels like something is missing.
Speaking of Hayden, I was confused by his role in the story. After spending the entirety of 2016 defending the UAC's use of Argent Energy, now he's totally gung-ho about destroying it. Maybe I missed a codex entry somewhere, but it's a complete 180 for his established character and I was waiting for some sort of explanation as to why he's suddenly turned from an ardent Argent supporter to the one leading the resistance against the demons and helping the Slayer stop its production. If it's in a codex entry (and it very well could be since the reveal that VEGA might be the Father is only really speculated if you bothered to read the codex entry), then I wish the game took more time to show that within the story itself.
On the whole I enjoyed Eternal. From a story perspective, I'd say 2016 had the better story since it's tighter and you didn't necessarily need to read the codex to get an idea of what's going on. Eternal takes some time to find its footing I feel, but once it does its firefights match and in some cases exceed that of 2016's. At the same time I get the feeling Eternal's gonna be a bit controversial given the discussion in this thread, but it's still a worthy successor to Doom 2016 in my opinion and a giant love letter to id fans in general.