Disclosure: I'm a 50-something gamer with a moderate reaction time. I enjoy first-person shooters, but it's not my favourite genre. And I only played the solo campaign; I have no interest in playing endless deathmatches against teenage whiz-kids who know the maps better than they know their bedrooms.
I enjoyed this game's variety of settings, from rocky canyons to urban plazas and of course a lot of hallways. There were even some flying missions that were a lot of fun. The graphics are great and the gameplay is smooth. Loading times are short. As a player who dies a lot in large battles, I appreciated the fairly frequent auto-save checkpoints. It was challenging for an old guy like me, but not impossible. There were a few battles where, after trying multiple strategies and paths, sometimes you just have to run full tilt into and through the enemy lines. I liked how this game led right into the opening for the original Halo: Combat Evolved.