NOTE: I previously posted this review on GamePro.com

One of the most stunning technical feats on the PS1.
I
have to admit that for years, even I just assumed that the N64 version
of Quake II was the superior version of the game, so I overlooked the
PS1 version. Boy do I feel dumb.
QII PS1 is a technical marvel
considering how graphically intense the PC version was at the time
requiring a top of the line 3D accelerator to run. How could they
possible make a decent port to the PS1? They didn't even port the
original Quake to the system because because they said it couldn't
handle it, but yet they made Quake II, and It's a damn impressive port.
I'm
not sure what Hammerhead did to get these kind of results out of Sony's
old grey box, but the PS1 version of Quake II is the most impressive
console port of the game (not counting the 360 port). It runs at a
smooth 30 FPS with a little slowdown in a few areas. It also has better
lighting effects than the N64 version, and just runs a lot smoother than the N64 port does.

The PS1 version more closely follows the PC version than the N64
version. Instead of being a completely new experience, Hammerhead opted
to try an include as many of the originals levels as possible (though
there are some that are MIA), and it even retains the original music.
This game just feels more like Quake II than the N64 version.
QII's
design has expanded more from the get the key to open the door to a
more objective's based gameplay. The level design feels like a
precursor to Half-Life in some ways. There are what you could call
levels, but they're huge and are divided into multiple areas that the
game loads in. You can even, and actually will have to back-track to
previous areas at points in the game giving it a more Half-Life than
Doom feel.
It's not big on story, something about the Strogg
(Borg-like creatures) invade earth, and your company is dispatched in a
covert mission to the Strogg homeworld to try and kill the leader. That
mission goes horribly wrong during the invasion, and you're separated
from the rest of your company who is decimated by the Strogg defenses
leaving you as the lone "Doomed Space Marine." It's a pretty typical
story, and QII is more focused on action, so the only progression of
that story comes in getting new objective sent you way from your
command ship.
Quake II's gameplay is simple. You fight your way through hordes of
Strogg baddies along your way to fulfill your objectives. The
adrenaline pumping gameplay really makes you feel like the lone badass.
No hiding like a sissy for your little shield to recover, just run and
gun, and kick some ass, and pick a heath pack here and there if you're
low on life. It's pure run and gun gamplay, and that what I love about
it. It keeps it simple, and sometimes less is more. The shooters of
today try too much to be these big cinematic experiences, but,
sometimes, you don't care why you're doing it, you just want to shove
you super shotgun up a Strogg Enforcer's ass and let the shrapnel fly.
QII may be primitive in nature, but it's still a blast.
While,
you won't find a control scheme that completely mirrors the dual stick
control of today (though the "Right Stick" is the closest with movement
w/ the d-pad, aiming with the R-stick, and firing with the L1 button),
most of them work smoothly, and the game even supports play with the
PS1 mouse.

Another great feature of the PS1 version is four
player split screen multiplayer. I can't vouch for how smooth it is
with four players, but I've played it two player, and have seen vids of
three player matches, and the game still ran buttery smooth. There
aren't many games on the PS1 that even support up to four players let
alone many (if any other) FPS games. This is the PS1's best answer to
Goldeneye for four player deathmatches, and it's a blast.
Bottom Line:
Quake II on the PS1 is not just an impressive port, but a very fun
game. Some of the newer FPS player will be turned off by it's oldschool
gameplay, but those who love the old FPS would do well to pick up this
PS1 port.
Here's a vid I uploaded to youtube of the game in action (as played on a PS2 with Texture Smoothing on):