Well, to be honest. . . Yes, there's enough stuff in Perfect Dark to keep you busy for a loooong time. I don't think I can accurately describe the sheer amount of stuff to do in Perfect Dark. One of the cooler things you can do is name and create your own character from any of the in-game characters (with interchangable bodies and heads). Then, as you use your character, the game saves ALL his/her/it's stats. How far it's walked, how accurate it is, how much damage its dished out, just about everything. This is just ONE of the multiplayer options. I love it. I can't honestly do the game justice with words.
The framerate. Let's keep in mind kids, that IGN (and I'm sure plenty of other people) likes to **** and moan about every single framerate inconsistency in the world, no matter how insignificant or undetectable. The only situtations that might noticeably hurt the framerate is if you: have the game set on hi-res (which is kind of pointless anyway), have 4 people playing and 5+ computer players too, or if you have 12+ guards on screen blowing up cars and shooting at you.
If you even remotely enjoy first person shooters, you must own this game. :)
After Perfect Dark, other shooters just don't compare. (my personal opinion)