I would have loved to see a Dual-Socket MOBO allowing Xeon-SP, but that would certainly get extremely expensive -- simply do to the pricing of these CPUs. That is the true high-end of the workstation market. As a single socket workstation, this thing is as capable as anything else out there. It's not revolutionary per-say, but it is quite capable as a base for the next 5 years at least. The form factor is what everyone wanted more or less, so great.
I wonder if they allow overclocking of the CPU base clocks since they claim their heatsink can dissipate 300 watts and the top standard Xeons only reach 205watts at the moment. That would be interesting. If they can overclock such as
https://www.asus.com/us/Motherboards/ROG-Dominus-Extreme/
..then it could be quite interesting even in comparison to dual socket workstations.
The MPX format is semi interesting. I suppose it exists mostly to avoid cables and to have a proprietary format to "assist" pricing justifications. But it is very cool of them that they also included standard power cables on the MOBO to use standard high end GPUs if desired. Now where are the Nvidia options? It will be interesting to see how 3rd parties use the MPX format for non-GPU things, like the Promise RAID expansion.
The pricing for the base specs are as others have already commented. The case, mobo, fans, PSU, heatsink, and general engineering of all of this into an impeccably designed coherent package with the ability to run OSX without risk/headache has definite non-trivial value though. I'd almost like to see a barebones option WITHOUT CPU, RAM, SSD, GPU etc since none of that is Apple-made anyway. Just give the Apple parts and let customers put in exactly what they want, since it is commodity anyway. It'd be interesting to see the pricing of such a barebones option. I think it would be quite fair to charge a premium for such a thing, the question is how much of a premium.
If you are buying this, you should put the 28-core CPU in it IMHO. (It has a $4500 retail cost -- will be interesting to see the Apple upgrade price.) A machine like this is NOT meant for 8-cores... It's silly to even offer it IMHO.
As a software developer, and as the first audio company to offer AVX-512 optimization, I am quite pleased to see Intel Xeons at the center of the Apple Pro machines for what I must assume must be at least a 5-10 year plan. Thank god there was not a switch to ARM! This generation of Intel CPUs are ridiculously fast! (I have the old cheesegrater, the trashcan, a Wintel 7980xe i9 machine, and a dual Xeon SP machine for comparison. There is no comparison whatsoever to the earlier Mac Pros, the 18-core 7980xe is almost 4x as fast as the 12-core Mac Pro trashcan -- to say nothing of 28 cores, or even dual 28-cores as is possible with Xeon-SP. Intel Skylake and later CPUs are insanely great! So a Mac Pro based around them is certainly VERY great news! Exciting times to be able to write software for such power!)