Very interesting and extremely impressive! I tried using the voice chat in their app previously and was disappointed. The big UX problem was that it didn't try to understand when I had finished speaking. English is a second language and I paused a bit too long thinking of a word and it just started responding to my obviously half spoken sentence. Trying again it just became stressful as I had to rush my words out to…
I do my work in english and talk to people just fine, but with machines it's usually awkward for me.
Also on your other note (demo seems to be very rambly), it bothered me as well. I don't want the AI to continue speaking, while having nothing to say until I interrupt it. Be brief. That can be solved through prompts at least.