I care about subpar textures, look at a game like Crysis, its not like "Oh the last mission is amazing, everything looks photorealistic, so I can forget about the first mission where it looked like an Xbox game" now is it? Being consistent is hard.
And I assume some of these gameplay stages are fight scenes, either the battle with Snake and Liquid at the end, or the mech battle.
Then in these sequences the game should be treated as a fighting game, and not be compared to other shooters/action games etc. Compare it to SC4 or T6 or something.
Any dev, can make a scenario with a limited environment, and few onscreen characters look amazing. Just look at Ninja Gaiden DS, all the boss battles are rendered in full 3D, while the rest of the game is 3D characters over 2D prerendered backgrounds.
In response to whoever criticised my attempts to compare the graphics of COD4 and the MGS4 demo level:
I understand that the games are not identical in gameplay.
Yes the AI in COD4 is stupid, but that is compensated by the fact that there are som many of them (including friendlies) on screen at a time. And the AI in MGS4 is hardly impressive, Ars Technica's review of the game said the AI was barely improved from MGS2.
And in COD4 yet despite the storm of bullets flying through the air (which interact realistically with the environment remember) and the ridiculous amounts of grenades been thrown (which explode with impressive particle effects, unlike the woeful effects of the petro bomb in MGS4) the framerate rarely drops, In the MGS4 demo level at the end with the artillery fire the framerate was in the 20s or less. And COD4 runs normally at a much higher framerate around the 50 fps mark.
The argument that COD4 forces the player to stick to a narrow path due to enemy fire is also baseless, play on Recruit difficulty if you find it too hard to run between cover. In Charlie Don't Surf there are quite a few different paths available to take to get to the TV station, certainly as many (if not more) paths available in the demo section of MGS4.
And some missions like Safehouse, let you explore the entire area and choose where to attack, at your whim.