The D6 is still there for a handful of things - likelihoods, a few tables... but a D12 is basically just a D6 with twice as many sides, so it's a straight up conversion to move to D12 as the only die you need.
Well that's nifty.
I like it that you never wonder which die to roll this time - if you're rolling, it's a D12. I also like the change for likelihoods, because then I can stagger them a bit and put them on a bit of a bell curve:
- Very unlikely 1 only
- Unlikely 1-3
- Possible 1-6
- Likely 1-9
- Very likely 1-11
I think it's easy enough to remember - the front and back end end in 1, and the middle three are all divisibly by 3. So it's 1/3/6/9/11. Not hard to remember, and better represents the descriptors. Something that is very unlikely should occur less than 10% of the time, so that's solid.