OK so here's the skinny - It's a really friggin good game but has some clear flaws and some definite low moments, but I still absolutely recommend it.
If you're interested in playing it, though, there's a bug that occurs with modern graphics cards where it freaks out and forces you onto the lowest settings for some bizarre reason. Here's the fix: https://www.gog.com/forum/quake_series/quake_4_low_res_texture_fix


(Note- I played this on "lieutenant" difficulty, which is harder than normal but not the hardest. I'm also not quite at the end, but I am approaching it.)
Quake 4 does a lot of things really well. Most of the guns feel really good to fire, it has genuinely impressive ally AI, and it has some SUBLIME atmosphere, particularly in the middle third of the game.

I'm not gonna lie though, you may be very easily turned off by your first impression. For the first, say, hour and a half or so, you have some pretty weak movement speed that is frankly just frustrating. This is later fixed by your character getting bodymods, but it shouldn't of been like that to begin with. You're not given access to many decent weapons, and you just generally feel pretty weak at this point. This is also where the game has the most vehicle segments, which are far and away the worst parts of this game (although they could very easily be much, much worse).
But even during these early parts of the game, you will still get a good game feel from the way the combat plays out and just how good the environments are sometimes.

Thankfully, the game does eventually find its footing, and it goes from a "fine" to a "genuinely solid" game very quickly. Your movement speed increases, you get a wider array of weapons, you're learning more about the flow of combat, and all along the way, you get to take in the oppressive atmosphere. Seriously, they do a magnificent job of making the Strogg feel like a ****ed up alien entity that absolutely needs to be eradicated.

There are a few issues I have with the main gameplay loop, however:
-Here's the big one first. Enemies feel kind of bullet-spongey. This is probably due to the difficulty I chose, but I feel like the amount of damage I TAKE is perfectly reasonable and a fair challenge. But it is annoying when I have to shoot a low-tier enemy with a shotgun five times at point blank range before he goes down. (Sometimes they take 1 shot tho, I dunno, it's really inconsistent)
-This game has one of the weakest sniper rifles I've ever used. Seriously enemies don't even have a flinching animation when they're hit, I can put like 3 entire rounds into them before they die, and it doesn't feel like I'm doing anything at all.
-Like I said, movement speed in the first third is just pointlessly slow, that should've been changed.
-Level design feels a bit overly-streamlined at times. This is one of those games where they use the same door model over and over but just leave the ones you need to go through conveniently unlocked. I feel like there was probably a better way to handle it.
-This is kind of a nitpick, but grenade physics are really bizarre. It can be hard to bounce them around corners because sometimes that just bounce directly back at you, even though you aimed it at the wall at an angle.

My final verdict is that although Quake 4 feels like it borrows heavily from Half-Life's FPS formula, it still feels like it gets Quake at its core: Combat that revolves around picking the best weapon for the right time. If nothing else, it gets that right. Heck, the story ain't bad either. It won't win any awards, but it did an excellent job of elaborating on what was setup about the Strogg in Quake 2 and making them a much more formidable foe. At the end of the day, if you're down for a schlocky mid-2000s shooter, Quake 4 has got you covered. You could certainly do a lot worse for 15 bucks.

OK so here's the skinny - It's a really friggin good game but has some clear flaws and some definite low moments, but I still absolutely recommend it. If you're interested in playing it, though, there's a bug that occurs with modern graphics cards where it freaks out and forces you onto the lowest settings for some bizarre reason. Here's the fix: https://www.gog.com/forum/quake_series/quake_4_low_res_texture_fix (Note- I played this on "lieutenant" difficulty, which is harder than normal but not the hardest. I'm also not quite at the end, but I am approaching it.) Quake 4 does a lot of things really well. Most of the guns feel really good to fire, it has genuinely impressive ally AI, and it has some SUBLIME atmosphere, particularly in the middle third of the game. I'm not gonna lie though, you may be very easily turned off by your first impression. For the first, say, hour and a half or so, you have some pretty weak movement speed that is frankly just frustrating. This is later fixed by your character getting bodymods, but it shouldn't of been like that to begin with. You're not given access to many decent weapons, and you just generally feel pretty weak at this point. This is also where the game has the most vehicle segments, which are far and away the worst parts of this game (although they could very easily be much, much worse). But even during these early parts of the game, you will still get a good game feel from the way the combat plays out and just how good the environments are sometimes. Thankfully, the game does eventually find its footing, and it goes from a "fine" to a "genuinely solid" game very quickly. Your movement speed increases, you get a wider array of weapons, you're learning more about the flow of combat, and all along the way, you get to take in the oppressive atmosphere. Seriously, they do a magnificent job of making the Strogg feel like a ****ed up alien entity that absolutely needs to be eradicated. There are a few issues I have with the main gameplay loop, however: -Here's the big one first. Enemies feel kind of bullet-spongey. This is probably due to the difficulty I chose, but I feel like the amount of damage I TAKE is perfectly reasonable and a fair challenge. But it is annoying when I have to shoot a low-tier enemy with a shotgun five times at point blank range before he goes down. (Sometimes they take 1 shot tho, I dunno, it's really inconsistent) -This game has one of the weakest sniper rifles I've ever used. Seriously enemies don't even have a flinching animation when they're hit, I can put like 3 entire rounds into them before they die, and it doesn't feel like I'm doing anything at all. -Like I said, movement speed in the first third is just pointlessly slow, that should've been changed. -Level design feels a bit overly-streamlined at times. This is one of those games where they use the same door model over and over but just leave the ones you need to go through conveniently unlocked. I feel like there was probably a better way to handle it. -This is kind of a nitpick, but grenade physics are really bizarre. It can be hard to bounce them around corners because sometimes that just bounce directly back at you, even though you aimed it at the wall at an angle. My final verdict is that although Quake 4 feels like it borrows heavily from Half-Life's FPS formula, it still feels like it gets Quake at its core: Combat that revolves around picking the best weapon for the right time. If nothing else, it gets that right. Heck, the story ain't bad either. It won't win any awards, but it did an excellent job of elaborating on what was setup about the Strogg in Quake 2 and making them a much more formidable foe. At the end of the day, if you're down for a schlocky mid-2000s shooter, Quake 4 has got you covered. You could certainly do a lot worse for 15 bucks.