It's baffling how out of the classic Doom games, only 1 is good. 2 Is too big for its own good, with a scale that does not fit the gameplay, and this one either falls into the same trap (it even just reuses some Doom 2 levels) or shoots itself in its own foot with new design approaches.
The shotguns have worse and lifeless reload animations, the overall redesign of a lot makes it feel like a cheap knockoff more than anything else and the atmosphere does not mesh with the game.
Levels are more confusing than ever, and they decided to adapt something from Quake - where you have to shoot buttons sometimes in respect to a 3D environment. Only you cannot look up and down like in Quake, so the game may ask you to find a spot where you match the height of the button and then shoot it. Good luck even figuring that out after wandering the empty halls in confusion for a while.
Rounded up with a final boss that is either ridiculously difficult or easy depending on if you found some secret levels. Seems like it is only a balanced fight when doing one or two of the three secrets, as otherwise you are either both overwhelmed and weak or underwhelmed and overpowered.

The -ideally- final installment of a 2000s FPS series that already displayed in what direction the developer would go. In our reality, it is not only a splitting point for Bungie but also for Halo, as 343 decided to further build on this game isntead of going back to Halo 3.
The campaign is decent with an unusual approach to grittyness for the series that works in execution, but I have to say the story isn't one of the greats. The premise of fighting an already lost war is delivered really well but the actual writing can fall flat and characters are mostly archetypes with their best scene being their deaths.
Gameplay works for the singleplayer, although melee is ridiculous in this one. Sure, Spartan IIIs are weaker than the Master Chief, but being nearly one-hit by the elite's turbo speed punch is insane. Almost as banal as Halo 2.
The weaknesses of the gameplay really shine in the multiplayer. It is an unfun mess lacking the beauty of Halo 3's abilities while failing to balance maps around sprinting, jetpacks and the other recharging power abilities. Add bloom to the party and you have a shit experience.
It is saved by forge and custom games, where it has some nice additions resulting in more fun modes.
Firefight also makes a return here and I can't say its either better or worse than ODST, as both have their strengths and weaknesses. Both are a fun time but there are far better iterations on that concept outside of Halo.