I absolutely loved it. It was a good mix of the few things I like about Doom 3, the fast paced slaughter fest of the originals, and a bit of mechanics from the Quake series too. Honestly I hope they release a ton of DLC that add plenty of news levels, because this is definitely a gem for sure.
I'd be willing to call it the number one FPS of the year, because I don't anything else will be as *fun*. Sure some of the generic shooters are "fun", but this one is genuinely 0 BS absolute fun.