True to their nature as a technical site, what impressed Ars most about Halo 3 was its solid framerate:

The truly laudable aspect of the presentation is the solid framerate. There are times when you'll be fighting in a congested environment, full of enemies moving and firing of their own accord, only to see overhead Pelicans and Phantoms weave through the air, dropping off more enemies and blasting at each other. Or perhaps you're coming over a crest with a crew of Warthogs following you before a pair of Scarabs fall from the heavens, landing on an encroaching horde of Wraiths and Grunt-driven Ghosts. During these intense moments, the game never loses a frame. Even in the most intense sequence of the entire game that comes as a climax just before the ending—which includes countless explosions, tons of enemies, and some insane environmental destruction—the game's pace stays rock-solid.

However, Ars found other flaws, such as "deceptively small environments" and the shortness of the campaign (they played on Normal, keep that in mind) and rated the game only a 7.