I had a little hands-on time with the new Mac Pro yesterday, and a few things jumped out at me right away. First: It's really small, and no matter how many size comparisons I've seen it still seems too small to be a top-of-the-range workstation-class machine. Second: It's really heavy—even more so when you consider the size. This thing is surprisingly dense, and the hollow in the top gives it a sense of emptiness that makes the weight even more notable. Third: It's crazy-fast. Launching a few fairly sizable applications (Logic Pro X, Aperture) was essentially instantaneous. Moving over to an i5 iMac and doing the same thing made the difference even more noticeable. Techcrunch noted this in their review too:

For the layperson or everyday computer user, the new Mac Pro will seem like a thought-based computer, where virtually every input action you can think of results in immediate response. Whether it’s the Xeon processor or the super-fast PCIe-based SSD or those dual workstation GPUs, everything seems slightly but impossibly faster than on any other Mac, even the most recent iMac and Retina MacBook Pros. To be honest, it’ll be hard to go back even for everyday tasks like browsing the web and importing pics to iPhoto.

But that’s not what the Mac Pro is for: It’s a professional machine designed to help filmmakers create elaborate graphics, 3D animations and feature-length films. It’s aimed at the most demanding photographers, working in extreme resolutions and doing batch processing on huge files. It’s for audio producers, creating the next hit album using Logic Pro X and low latency, high bandwidth I/O external devices.

It's certainly going to be hard for anyone who's not using their Mac for serious production work to justify this level of a machine, but make no mistake: This is the kind of user experience that Apple is shooting for, and I wouldn't be surprised to see it in much more mainstream computers in a couple of years. And once you've experienced it, everything else will seem slow.