Gears applies the principle of implied detail. Turn down the lighting work with dark browns, blacks, and grays. Make ample use of the engine by leaving blank spaces, and run the game as close to the rail as you can. The result is most people will think the game looks sick. The game F.E.A.R uses the exact same formula to great effect. Your being awed just as much by the designers skill as hardware power.
A good lay example would be the movie alien. Denying the audience a clear view of the creature gives their imagination more to do, and invariably they create their own vision of the monster. Which usually is far more customized to individual fear, and more importantly ignorance is very terrifying. Buy the directors cut and see the deleted scenes when you take the creature out of the dark, and into the light it looks pathetic, and much less intimidating.
Technically Halo 3 very well might make better use of the hardware then Gears. They are obviously two different styles which makes it hard to judge. However for a fraction of players Gears looks quite awful. Personally I found the game painfully ugly.
I outright object to the textures that thwart distinction. The black spaces in the field of view. Being black does not change the fact that its the same fog I used to loath in Turok, or Goldeneye. I abhor a lack of diversity in effect. I want to see glint, blooms, blur, and distortions. I want to see a larger pallet, and I do not want to see every texture grimy. How easy is it to make something look clean and look real. Compared to making something look dirty and real.
The answer is tastes are personal, but there might be no graphical difference between the games. They just use the graphical power differently.
