I consider it probably the best gaming benchmark out, but the 3DMark score is USELESS.
That is the frustrating part for me, the bench is very detailed and breaks down nearly every aspect of video card performance, but people focus on the useless 3DMark score.
Fillrate test for both sigle and multitexture, 
High texture load performance,
T&L performance,
CPU performance,
Full D3D feature test,
And a complete readout out of every feature, game related or not, that you board supports under DX. I think for 3DMark2K1 they should drop the 3DMark score and make people look at the numbers the test is generating. The 3DMark score itself is a great indicator of how the "MaxPayne"(If I recall properly) engine should run, much as UT is a good indicator of how UT engined games will run, but not overall DX performance.
3DMark2K is, IMHO, the best DX bench that is out, it just horribly misused by too many people.