I decided to pick up just one of the China Glaze Tranzitions polishes: Shape Shifter, a steel grey that changes to a saturated blue-ish purple after the addition of topcoat.
This is Shape Shifter before the addition of any topcoat; a slightly frosty gunmetal grey.
Below you can see my clumsy attempt at doing tips using a clear topcoat to change the colour of Shape Shifter; while it's kind of neat to see the gradual colour change after applying topcoat, it also makes it a touch harder to see where you've already painted while you're in the process of applying. I'm not sure it makes a better alternative for nail art- I'm not sure why one wouldn't just use another opaque nail colour altogether (although, admittedly, it's kind of cute to have "two shades of polish in one"... perhaps less so when one already has an absurd amount of nail lacquer).
Finally, the best result: Shape Shifter, fully top-coated. Gorgeous, deep, glow-y purple. Extremely pretty, and my reason for buying this in the first place.
Did you bother picking up any of the China Glaze "Transitions" shades? What did you think of them?