Blizzard Twitter:
"The #StarCraft2 programming team is optimizing the interactive story mode for all graphic settings, especially "High"."

Avarius:
"The changeling's transformation is permanent. Once it is within range of opposing forces, it will transform to that race's basic tier 1 unit (marine, zealot, or zergling) and remain so for its duration. In the case of a team game or FFA where there are multiple races, the changeling will transform to the race it encounters first and not change again.


Are the changelings actually useful in high level 1v1 play? Honest answer.

I definitely think you will see them used effectively, even in high level 1v1 play. Who wouldn't want an essentially free scout (only costs energy) to use to gather intel on their opponent? With the potential that you opponent might not kill it immediately, it can provide you with a sustained scouting advantage. Even high level players can get caught up in harassment, or base management and may miss this little guy sneaking into their base."