As a 3D artist, I have long since moved on from the Mac Pro but still recommend them to those that don't need the specific high-end features I do. Still, I can't help but be disappointed about the new Mac Pros due to one key component for me and that is a high-end nVidia graphics card like the 480x.
Several of the high-end 3D art programs I use have better bench marks, not to mention features that you just won't get with ATI boards. Some of the software I use cost up to $3,000 so it is not an option for me to use anything but. Since those programs take advantage of things like CUDA, FEMI and shaders specific to nVidia, that is a deciding factor for me.
The ATI 5870 is a nice card and will perform well for most consumers, even those that would like to game. But with no nVidia options that really seals the deal for someone like myself.
I would also have thought there would be USB 3.0 too but at least some of the more main stream consumers will get some use out of these updates.