I'm going to disagree with you here, Rie wasn't a bad choice for first guest. She does a lot of behind-the-scenes work for the music production, and she's got a lot of songs on her channel. She obviously has some talent musically and for presenting, which makes her perfect for this sort of show.
I actually felt Rie was underutilized - I would have had her talk a bit after each song. After her own songs, she could have talked a bit about how she approached making the song, whether it be what inspired her or what goes into making an original song, whatever. After another person's song, she could have talked about what she really liked about the song, what it did well, or if she was involved in any behind-the-scenes production.
The format does need work though. I hope Rie can come on another time when they improve it.