I bought this game having played 007 quite a bit, which was made by the same people and is one of the greatest N64 games ever made.  The advantage that Perfect Dark has is in the multiplayer combat.  In addition to friends, you can have up to 8 computers playing in the game, with any combination of teams that you want.  This is fun with several real friends, or just for playing by yourself against others.  The AI is smart enough to be extremely challenging at the hardest difficulty levels, or slow/dumb enough for a new player to learn against at lower difficulty levels.  Newer systems have better multiplayer capabilities (online, or hooking up multiple X-boxes for Halo parties, etc), but for the N64 this is as good as it gets (and if you like to play against computers instead of real people, then this is as good as any newer system games that I've seen).