I'm a bit late to the party, but after having read almost 40 pages of this monster thread I'd like to add my 2 cents as well.
First things first, I voted for a failure. Not because I think the nMP is an absolute failure in itself, but because there's no way around the fact the nMP is closer to a Mac Mini than a Mac Pro. Does that mean the nMP is a useless product? Not at all, like any other product it has it's place and some people will love it. I think it's a great piece of engineering, although quite ugly if you ask me.
The problem as I see it, is Apple moving away from the pro industry and becoming mostly a consumer/prosumer oriented company. It's undeniable Apple hasn't been very focused in the pro segment, and we all have seen this coming. There have been signs of this for years. From the 'dumbification' of Final Cut, to the death of Aperture and the stagnation of Logic. We were their number one customer not so long ago, but times have changed. People are moving to Cubase, Premiere, Lightroom, After Effects, Avid, Live, etc.
And all this is not only about the death of
the Mac Pro and Apple's pro software.
Look at the current line of MBP. Here is an interesting article at Motherboard:
The 2012 Non-Retina MacBook Pro Is Still the Best Laptop Apple Sells. There's only 1 very expensive model with a dedicated GPU, almost as expensive as the nMP. The rest are simply fat Macbook Airs. 4 years later my 2011 MBP is in the same performance range as most current era retina MBPs. I know because I have both. So instead of getting 4 years of performance improvements in both CPU and GPU, we have thinner non upgradeable machines with lots of battery time. Why? Because performance is not a priority for Apple. Their focus now is on making anorexic lightweight products that generally meet most users performance needs, and that have to be renewed every 3 years.
( On a side note: It could even be argued that Apple never really cared about top performance. After all OSX has been consistently shipping with obsolete OpenGL versions, and Windows has had it's own "Metal" called Direct3D for 20 freaking years. )
An you know what? It's fine.
It's like a company that started making trucks and cars moving into the luxury car range. Is it wrong per se? Not at all, it's their business after all. If it works with the market so be it. The problem is of course if you want to keep buying their trucks in which case you have very few options:
1) You buy used or keep their last aging truck and pray the investment will last long enough
2) You buy one of their luxury cars with a relatively powerful engine and buy extra small trailers and attach them via thunderbolt
3) You get into the truckintosh thing, suffering every time you want to upgrade to a new OSX version (without ever having a 100% OSX experience)
All those options are compromises. From a business and practical point of view the most sensible option is simply to stop dreaming and move to a different truck company.
In my experience Windows 10 is as reliable as OSX. It is damn ugly and less user friendly, but it does every job you throw at it, and as a platform it's more flexible. On a hardware level a Windows workstation is a better investment than the nMP or an iMac. Not only because your money will last you longer, but also because you will be able to work with the latest and most powerful tech. Something that today is not possible with Apple. If you want to be on OSX you have to accept you are being left behind hardware wise.
There are rumours of a new Mac Pro in 2016 which will probably settle this argument once and for all, at least for me. So if/when the next Mac Pro is released we will see if Apple is saying a) "We don't make trucks anymore, if you want one go to the competition" or b) "We want to regain the truck market segment". I hope they release a new cMP, but I sincerely doubt it. After all they made a huge investment in the nMP.
Personally for the last 5 years or so Apple has let me down consistently. They just keep making decisions that don't make any sense to me, and I don't see why this should be any different now. 2016 will the year that either Apple wins me back or I completely move to Windows again.