I finally heard all five songs from Batch Six as well as heard enough info that I need about the Drama CDs for me to evaluate on each of them. So, here we go.
Syoko: IM@S DEATH METAL, HELL YEAH!!!!!!!!!!!!!!!!!!! On a serious note, Syoko had a pretty good song overall. Its different from the rest of the Cinderella Master songs and I think it paid off in the long run. The only issue is that some of the melody felt a bit off, but nothing that actually hurt it. Syoko's character is actually so depressing for me now that they confirmed that her "GO TO HELL!" persona is all part of social isolation. Poor girl.

This ranks her up with Chihaya to me as possibly the most tragic of the characters in this franchise. Makes me want to give the poor girl a hug.
Nao: Easily my favorite song of the five! Nao's singing voice sounds so wonderful and the beat to the song is incredible. I heard the overall composer has done other works, including for iM@S, and after this, I REALLY want to check it out!

Nao, from what I hear, showed quite a bit of her soft spot in her Drama, which is always nice to see from somebody whose original Normal Card made her looks like sort of a bully. No offense, that's just the vibe I got.
Karen: Karen's song wasn't bad. It was just......generic. Don't get me wrong, its well-done, its just that I've heard this style of song before. Kinda makes me think of a trope called Award Bait Song (
http://tvtropes.org/pmwiki/pmwiki.php/Main/AwardBaitSong) which makes it remind me of songs such as "My Heart Will Go On" by Celine Dion from the end of Titanic or "I Am The Wind" from Castlevania: Symphony of the Night. (though I'd MUCH rather hear Hakka than I Am The Wind) Karen's Drama didn't do much from what I heard, but it is good to see Karen's overall development from her intial days of always having short lessons due to her illness. Character Development is beautiful, isn't it?

Sae: Catchy. As. Hell! I am serious! I had her song, Hanakanzashi, stuck in my head ALL DAY Friday! It's so awesome and catchy! ESPECIALLY that chorus! Sae had some light shed to her character as she is now shown to be a nice deconstruction of the usual Yamato Nadeshiko character. Polite and lady-like while still being fun-loving and mischievous. Ya know, like a kid her age should be.
Yuko: I gotta say........ Yuko was probably my least favorite of the bunch. Possibly of the entire Cinderella Master collection. I mean, her song isn't bad, it just.....didn't do anything for me. It wasn't well-composed and sung like Nao's, it wasn't unique like Syoko's, it wasn't catchy like Sae's, and it wasn't Celine Dion/Whitney Houston-inspired like Karen's. So, what is it? I guess I can say it isn't another love song (from what I can gather so far), so that's something? :/. Also, her Drama did little to nothing for her character. She's still just a girl who thinks she's psychic. I kinda feel like Yuko was chosen to capitalize on the current popularity of the chunnibyou character archetype.....even though we already have Ranko for that, who is a FAR superior character. Nothing against Yuko at all, she just....didn't do it for me. :/.