As I read and reread the December Playtest update for DnD Next, Skill Dice were the idea I had the most problems with. I like uniform mechanics in my RPGs and I hate it when Combat is one system and Skills are another.
This was exacerbated as I read various Special Abilities and Maneuvers that used Skill Dice. I kept wondering why the particular skill mentioned wasn't called out? What was wrong with WotC? I was pretty close to just walking away from DnD Next.
And then I realized the problem wasn't the rules, it was me. I was overthinking it. Your Skill Die is equal to X, depending on what level you are. If an ability calls for it, you don't have to worry about a Skill, just the Skill Die. It was beautifully simple.
Then, when making checks, I could just call for say, a Dex Check and mention the Skill Die if they were trained in Z.
Also, when making a Skill Check, there was visual cue during the roll that the PC or NPC was trained in a skill. The Die told you.
And for new players, I've found having the Skill Dis a concrete separation from the Attribute and helps them understand and more importantly want to use those Trained Skills.
I still like uniform mechanics, but I can't argue that the Skill Die works.
Good job, WotC.