They ruined the game when they replaced the Halo 3 spartan with the Halo 4 spartan
they ruined the game when they poorly implemented sprint and upgraded weapons
the unofficial version was ruined by its stuffty community that wants a carbon copy of halo 3 instead of a unique pc only halo experience a la halo custom edition
but also theres a mod for it that bring back the models for halo 3 armor and weaponry and they look fantastic with the shaders in halo online