The PC shooters that year didn't have combat any where near as exciting, memorable or challenging; so to call Halo one of the worst shooters ever made is fucking retarded.
Serious Sam (also released in 2001) wasn't memorable or challenging? I had loads more fun playing that than I did Halo. By the time you got to the Flood, the gameplay stopped being exciting and started being a chore. No thanks to the AI. Without those Elites, Halo would have been just as bland as Max Payne. What else was there to fight, the things shooting mortars at you? The floating robot sphere? The cowardly little peons? I would rather eat rusty nails than play though Halo again.