thats just you, baldurk.
not everyone thinks doom3 is the greatest thing on earth. it is, definitely, for rather low end systems. there it shows sort of the end of line of what an older gpu/cpu combo can handle.
hl2 has other targets, first of all definitely in gameplay with its physics engine. and second, the graphics are more.. bright, more indirect, than doom3, creating a much more ambient scenario. feels great in realtime, too. just as doom3 has its quality, hl2 does. and doom3 was delayed quite some bit, as well. it was once planned to come more or less with my radeon9700pro. that card is now 2 years old.