My Two Cents:

With few exceptions, I see Black Cleaver on AD and Blackfire Torch on AP are rushed first in every match.

So...yeah... Apen and Mpen auras became items? Yay(?).

I'm a little nervous on passive CDR, because needing to build CDR is about the only thing keeping AP builds that mix in durability supreme- and if anything I'd like more difference between high-damage high-cdr glass builds and tanky mage builds.

On the topic of build diversity, I don't like BFT because it feels like too much of a core item on almost every mage in the game. I'd rather it be more of a specialist item than a "everything you want but mana" must-buy.

Issues are rampant already with the nerf to resists. It really doesn't feel any different. Resists are pretty much still completely worthless on Dom.

I like turtles

I feel like now that people are thinking that resists are worthless thanks to the changes in penetrations and BC introduction, people are always getting the damages..

so right now dominion becomes more unforgiving and is now a "deathball game" and the only way to survive decent enough in a teamfight is by having 2500+ hp end-game at least.

I would just like the mouse cursor bug to be fixed. It has been problematic since Dominion was in beta and it's still not fixed. See threads about it all the time with out the problem being fixed.

I think that the passive penetrations leaving was good. It made dying early game incredibly easy. And Black Cleaver is fine (I think making it proc on only auto attacks would finish its polish).
I personally don't think that a passive 10% cooldown would help because that takes away from build diversity. If you want lots of cooldown reduction buy and use it. That will be the advantage of your build. That and some champions would quickly become out of control with early cooldown. Karthus comes to mind.

Black Cleaver + LW = you need 300 armor to effectively have 100.

Armor stacking is a noob trap.