I've got one; eight core, 32Gb RAM, Dual D700s. I've been enjoying it immensely. I was one of the people who didn't understand the whinging about the "external drives" and spaghetti mess though, my Mac Pro 4,1 had about a million cables coming off the back of it - four fibre cables, two ethernet, full video breakout, three monitors, firewire, USB, etc. The new Mac Pro has actually simplified things for me greatly - I finally upgraded my old Xserve RAIDs to a Thunderbolt 2 Areca system - that's four cables down to one and four times faster. Using Thunderbolt I've also been able to buy a Tb breakout dock to add a few USB3 and Firewire to my desk, Thunderbolt connects my video IO, it's actually much tidier than my old Mac Pro. It was a massive investment though - don't get me wrong - but a very forward looking one in my opinion.
But best of all? In a single pelican case I can put my 8-disk Areca RAID and my Mac Pro and have a full power workstation on site when required. It's not something I require often, but when I do need it boy howdy is it easy.