My personal reaction:
Apple truly surpassed my expectations, but that wasn't that difficult to be honest.
Will I buy it?
I have to admit I tend to, even as the machine is truly overpowered for me. But this is the age old problem of Apple not offering a similar modular(!!!) device without monitor, still decent but not as extreme as the new MP. But I guess we will never see that "xMac", so for me, an overpowered machine is still better than an underpowered/unsuitable one.
One thing that still holds me back though is the GPU situation. I really dontlike Apple going AMD only, and as the "MPX" module seems to be quite proprietary, can I still use a "normal" GPU even from AMD? Just in case Apple "forgets" to offer an upgrade later on ... Because if I really buy this, it has to serve me quite some time, i.e. I will need to upgrade my GPU about two times in its lifespan. So thats the biggest factor holding be back - also long time support in general, and still a lack of confidence that Apple does not change their minds later again regarding to the Mac Pro.
Other than that .... well ... NVIDIA? Hmmpf.
Still, I have to admit I slowly begin to like this machine! Looking forward to the first hand on reviews. Not looking forward to final pricing ... hope it is not too expensive to upgrade CPU and GPU a bit, as the entry config is a joke imho. RAM and SSD is not a problem imho, heck they even are already offering 3rd party modules for my 3,5" cold storage spinners as well. So my basic needs & wishes of mine are almost (see NVIDIA) covered, or even "over-covered".
Could be worse, right?