The Smashing Pumpkins musician, who was first romantically linked to the Veronicas singer earlier this year, said that she and her sister Lisa are "interesting" to watch while they're working on music together.
Corgan told The Daily Telegraph: "[Jess is] a really beautiful person inside and out. Those two girls are so talented. I was recently in a writing session with them. They could both be world class solo artists.
"It’s crazy they’re both together. They feed off each other’s strengths and weaknesses. It’s really interesting to watch them work. I really am impressed by both of them musically a lot.
"I’ve heard a lot of their new stuff, the direction they’re going is really, really cool. It’s still very much pop music, but they’re so sophisticated in their knowledge of pop music."
He also described his relationship with Jess as a "whirlwind".