Missing some content.
I originally wrote this for my Amazon review.
Quake 64 is a really weird port. It's missing some of the best levels from the base game. There's no Grisly Grotto, specifically, which means there's no secret exit to the Well of Wishes, which means the Dopefish secret is straight up gone.
The difficulty and episode selection hub that is somewhat synonymous with the game is also gone. You pick your difficulty from a menu, and the game drops you into E1M1. Progression is entirely linear, from one level straight into the next.
Control wise, well, it's an FPS on the N64. The defaults are atrocious, but thankfully you are able to set everything to anything you want. I was able to find a comfortable scheme after about 5 minutes of playing around with it. Some of the possible things you can bind are, well, questionable. Having the ability to hold a button and replace movement on the stick with aiming isn't great for a game like this. Splitting vertical aiming and horizontal aiming between the c buttons and the stick, and movement the same way, worked out the best for me, with reset view on dpad down, and jump on R. Switch weapons on A and B.
One of the concerns is the frame rate, and it is an issue at times. Single player mostly does fine, though I was playing with the expansion pack. When my friend and I went to multiplayer, things changed. We used The Dark Zone, Q1DM6, aka "The Map", and had frame dips down to what felt like 12 fps rather frequently. The status bar is moved from the bottom of the screen to the side in an ugly box for split screen, and while this can be disabled, doing so removes any kind of means to track your health and ammo. The ability to change your shirt and pants color is missing here, so everyone really blends in against the environments, especially when the frame rate tanks. It's very unfortunate.
As a historical piece, Quake 64 is worth looking at. If you want to play Quake for the first time, get it on PC.