I played through the Ultimate Doom with it back in like 2018, and jumped in for a bit today, and had a blast.

I see some reviews complaining about it breaking the balance of the game, which is like... duh. This mod adds several new weapons, (optional) reloading, ability to aim down sights, melee combat, AI companions and many many other things. Of course it fucking breaks the balance, it's a fucking mod, what do you expect? Which mod doesn't break the balance? The whole purpose is to alter the original experience and squeeze out some more fun from a game you've already beaten many times. The same people, who complain about this game messing up the original experience, never have any issues with "remasters," remakes, expanded editions and other alterations of perfectly fine games, even when they're horrible like that Mass Effect "remaster" that completely changes the core gameplay. At least Brutal Doom does not present itself as the same game.

As for the people rating it low because the creator of this mod is an asshole, I mean, a lot of professionals working in the video game industry are worse, you still play their games. The fucking big heads at Blizzard were doing their "Cosby suit" shenanigans and drove a girl to suicide, and you all play Diablo 3. Not to mention the million times they fucked over good people for money. Idk why suddenly everyone has a conscience here.