Ah yes, I noticed the live CC recently! I tried it out in a conf call between myself (very Scottish accent), a Swede, a Norwegian, an Indian and an American - it really was amazingly accurate for everyone!
That said, beyond novelty I'm not sure how useful a CC feature is.
Some of my students tell me I talk too fast, so it can be helpful for them to review content, and I've had quite a few students with varying degrees of hearing impairment. Pretty useful in my field.
That said, beyond novelty I'm not sure how useful a CC feature is.