4 really disappointed me, lore wise. I felt the characterization wasn't well done, and the Didact/Promethean Knights as enemies was confusing, especially in light of the Bear novels. But I'm the kind of guy who thinks some mysteries don't need detail, and the Forerunners were more impressive when we didn't know anything about them. Unrealistic, I know ;-) I'm probably never going to appreciate a Halo Title more than CE, though. I dunno, meeting the Didact and the Librarian was just a disappointment to this long time fan. 5 looks like it's on track though.