I always felt Ozeki brought a charm on par with Uta. I too can't stop watching just for her lines in the end and the beginning.
Chisaki needs to find her personality still, normally it's not a big deal, but everyone else have such strong ones already. If they're pushing her to fill Uta's shoes on top of it...
I'm hoping the Summer song is headed by the 'experienced' half like Koi Dorobou was
.