Did a big old update to the OP. It is pretty disappointing that what little they did with processors in BFZ appears to be all they plan on doing for now, but at least they seem to be pushing the power of the cards with colorless costs.
I think this is all the spoilers for today:
Posting others for completeness.
Random comments:
* Now that Mirrorpool has been officially spoiled, I wonder if it's a reference to My Little Pony, which had an episode with a thing called the Mirror Pool that could clone people, or if the shared name is just a coincidence.
* I like how Unknown Shores is usually a junk card but may actually be really good in this set. It's a classic example of the "Shatter is better than Terror in Mirrodin" phenomenon.
* Comparative Analysis seems like it could be really good. Hopefully they didn't print a blue 1-mana cantrip.
* The flavor text of Spatial Distortion is interesting. Could Planeswalkers actually be resistant to damage done by Eldrazi? By the way, if this effect looks familiar, it's a colorshifted version of the black Nameless Inversion... minus the tribal and creature type part.
* The two intro pack rare Eldrazi with colorless activated abilities seem alright.
* Tyrant of Valakut is disappointing, but Reckless Bushwhacker seems like it could be good, maybe even Constructed playable.
* Crumbling Vestige is a seriously neat design.
* Even in Two-Headed Giant, Gladehart Cavalry looks like junk.
* Walker of the Wastes is pretty neat. I wonder if other cards will care about Wastes.
* At first, I was disappointed by support, since I was thinking "isn't this the same as bolster", but I quickly realized that it wasn't, and I was surprised that this mechanic hadn't actually appeared appear. I was saying a few months ago that a "reverse bolster" might make for a good Phyrexian mechanic, but maybe a "reverse support" would be better. Inflict N - Put a -1/-1 counter on each of up to N target creatures.
* Endbringer is a pretty neat card. I'm not sure if it will be Constructed playable, but it's a definite Limited bomb.
* Jori En is a pretty good card. I was disappointed that she didn't get a card in BFZ, but I'm glad she did here.
* Stone Haven Outfitters is funny in how it seems like it's meant to combo with Skullclamp but doesn't actually. Plus, you know, Skullclamp is banned in Modern.
EDIT: As for the color pie of colorless, it seems like they're generally going for anything that carries a "distortion" flavor, which mainly seems to be a mix of black and blue effects. Endbringer entirely does stuff that artifacts have done in the past.