FEAR's graphics aren't poor, or horrible by any means compared to the Doom 3 engine or the Source engine. The FEAR engine is a lot like the Doom 3 engine except in Direct 3D, it has Per-Pixel lighting, advanced shader effects like shockwaves, etc... And FEAR has something that neither the source engine nor the Doom 3 engine has: Parallax Mapping. Go up to a brick wall in FEAR, or shoot out a big chunk of whatever in a wall or the floor, and you'll see that the texture has depth and space.
A lot of people think that FEAR has crappy graphics just because of the lack of texture variety, and when an engine is pumping out god knows how many particle effects everywhere, having a lot of textures along with the particles will really slow down a system. FEAR also uses shaders more extensively than Doom 3 or HL2. When you go into slo-mo, bullets refract space, FEAR uses parallax mapping, per-pixel lighting, particle physics, water reflections/refractions, shockwave effects, specular lighting, its really pumping out a lot of shaders and thatÂ’s what slows it down. HL2 or Doom 3 donÂ’t use nearly as many shader effects as FEAR does.
But where Doom 3/Quake 4 and HL2 get a leg up is in the texture variety. HL2Â’s environments look much more convincing than FEARÂ’s because HL2 isnÂ’t pumping out an ungodly amount of shaders like in FEAR. Because HL2 was easier on the shaders, Valve used the opportunity to use more textures. HL2Â’s environments have more variety in them than FEARÂ’s and thatÂ’s why itÂ’s more visually pleasing. Same goes with Doom 3 and Quake 4.