The truth is, Halo sucked compared to Goldeneye for N64 and other FPS classics. The only reason why it got so popular was because it was one of the best games for Xbox for a LAN.
My biggest complaint about Halo was the weapon system. I hate games with weapons like "assault rifle" and "pistol". The armory is very limited. I would have liked to see a much more extensive arsenal like something in Goldeneye or Counterstrike with more technical names for weapons (even if they're fictional). This would give you many choices for different assault rifles, etc.
The vehicles and 16 player compatibility with large maps helped the success of Halo a lot.