Hm, I tried to play Perfect Dark when they re-released it, but found it so primitive it's virtually unplayable. Yes Halo did make you run through corridors in both directions towards the middle of the game, the reason being they run out of time to make more content. And yes, the alien spaceship level could get kind of boring, and everyone seems to hate the Library, although I thought it wasn't bad as a change of pace. But there were also many great and seemingly original levels, I'm surprised someone wouldn't like them, but to each his own.