Here's what to expect:
GameplayThere is lots of new changes, all to make the campaign more intense. Ammo is less common than in the original making the chainsaw very important. You have new abilities to rip and tear. And the best part, none of it takes away from the stunningly simple, adrenaline-fueled gameplay.
The platforming puzzles have also been overhauled. Dashing and wall climbing are used frequently and creatively. Each level is crafted so well.
Cutscenes are more common but still very short and far between. Doom has always been a "gameplay first, story second" type of series and I'm glad to see that idea still being embraced nearly 30 years later.
Doom Eternal's campaign improves in nearly every way possible from the 2016 reboot. Everything is faster paced and more fun. The environments feel vast and breathtaking. You'll be fighting demons anywhere from tight corridors to giant god damn trains and there is so much room to move around and "doom-dance" your way through.
There are also tons of references to the classic Doom games from the 90s. In your lair theres a green suit you can purchase with Sentinal Batteries, which is a throwback to the original Doomguy. You can play Doom 1 and 2 inside of Doom Eternal (yes, I'm actually serious.) And this game really feels like the gamer's spirit of John Romero's original team was poured all over it.
PerformancePerformance is also surprisingly good. Even playing on a GTX 1050 my framerate rarely dropped below 40 fps and most of the time stayed above 60. Id Software added Dynamic Resolution to help and even added a VRAM meter to the settings. If you're on a mid-range PC this is a big step up. I would still recommend a GTX 1070 and an Intel i5 8400 for this game however.
MultiplayerMy only complaint with Doom Eternal is a lack of deathmatch. There is only one multiplayer mode, litterally called Battle Mode. It's a neat spin on typical shooters and is fun to play, but it doesnt have much to offer besides the gimmick of a 2v1 elimination with demons. I would like to see a deathmatch mode added in the future. Multiplayer is a great part of many games and can add lots of replay value. Doom Eternal is a great game and being able to play something like this more would be great.
Community contentUnfortunately Snapmap was removed from Doom Eternal, and theres not really much to expand with besides third-party mods. This again is detrimental to the game's replay value, however the overall experience in the rest of the game is still well-crafted.
ConclusionIt's understandable that Id may not have wanted to waste time on doing something they'd already done before. They wanted to spend their time improving Doom and really focusing on making the gameplay shine through, and it really shows. The developers poured their heart and soul into every corner and crevice of this game. Everything feels fluid, fast, and fun.
Not playing this game should be a crime. If you have the $60 USD to pay for the game, definitely give it a spin.