1: It stresses shader power too much over fillrate. The default settings in 06 (which are the ones used in all the scores you see) are 1280x1024 with no AA, but there are tons of shader effects used. This is why, for example, the 3870 often defeats the 8800U in it despite being slower in games.
2: The current version, 06, is almost three years old, and even that is just a minor update of 05 with HDR added in.
3: It's unrealistically dependent on CPU power and multiple cores in particular, more than any actual game. This is even more so now than it used to be, since video cards have gotten much faster since it came out.
4: The predetermined camera angles (combined with the widespread usage of the program) allow Nvidia and AMD to make heavy optimizations to inflate the 3dmark scores, much more than they could do in a real game.
The only thing it's useful for is to make sure that your system is running properly and you're getting roughly the same scores as other people with the same hardware. It's not much good for comparing different setups.
