I played the beta for the game and I actually liked the new mode they added called "War". It's not a new mode to FPS gaming, been around for years, but it's an attack/defense mode where people have an objective, rather than just running around with bad spawns and killstreak hell in the normal multiplayer. Multi-staged linear objective map that is actually fun. Genuinely surprised as I haven't felt like that about the series since Black Ops 1.
Then I played regular multiplayer and it's the same chaotic, unfun, mess as always with bad spawns, killstreaks that reward already winning teams, one hit kill quick shot snipers, and that really put a damper on the experience. There's good ideas, but it's held back by being a Call of Duty game lol
I don't personally mind a return to WW2, though other wars would've been interesting, though most other wars wouldn't make for a good shooter. Battlefield 1 worked well enough though. I wouldn't mind seeing Vietnam again and in particular, I'd like to see them do a fictional war, like they did with Bad Company 2.