I would recommend Goldeneye
over Perfect Dark. I have and enjoy them both, but even in one-player mode, the framerate in Perfect Dark is so choppy that the game is often rendered unplayable - forget about the higher difficulties, because the extra enemies onscreen often push the FR down to 10 fps.
That said,
in theory Perfect Dark does improve on the multiplayer experience substantially.
I've noticed that when you play the older N64 games long enough, you get used to the "less refined" graphics. And when you move back "up", you get to be pleasantly shocked all over again at the great PS2/XBOX/Cube graphics.
steve