I think 10th gen did VERY well, but they looked really green (That's to be expected right? They are very new). Masaki's low voice is a treat and I would prefer she use that in recording (I thought her line in Kanashiki Koi no Melody was jarring because she went so high). All the girls can sing, none of them went out of tune - which is rare for a gen, really.
Haruna is the weakest singer, but it's because her singing voice is soft, once she learns power I think she'll be very strong. She has no experience singing at all (Unlike the other three) so I'm actually expecting good things from her. She's behind everyone right now, but she's working REALLY hard (As it's mentioned in like, everyone's blog

). Give her a year and I'll think the world is going to be surprised. I love her determination <3
Ayumi is a powerhouse and Riho is right in saying she's her rival, I honestly think in 6 months Ayumi is probably going to pass Riho in terms of singing and performing. This isn't to say Riho is bad, it's just that Ayumi is THAT good. She's pretty amazing, really.
Masaski, as per usual, reminds me of Eri. She has a good voice there, but she's shy and it will take a couple years for her to fully develop herself. She doesn't have the Eri trademark sweetness in her voice, but her voice is really good. I feel like Eri was hiding her good voice for many years, till she hit about 16 or 17, I think the same may happen for Masaki. I love her though, I think Masaki is boss. My roommate is a HUGE Masaki fan, so it's nice to see she's getting support.
Haruka was good, but I expected more coming from an egg. That's sad to talk like that about a 12 year old, but it's true. I think Haruka is good overall and OMG I LOVE her voice - honestly her voice is probably my favorite out of 10th gen, I just want to see her pop a little more. I don't think she's shining as much as the rest of her gen yet, but I expect good things from her.
I call 10th Gen the gen that's full of potential, Tsunku was right on the money picking these girls - they are good.
New S/mileage Members:
Rina is a good singer, but her stage presence is lacking. I don't know she kinda fades into the background.
I know a lot of people love Akari, but I find her a bit lacking at well. Her singing is okay, her dancing is GREAT. I really don't like her hair either

Kana is the shy one of the group and it shows. She's the weakest singer and dancer, I think she's improving but right now I think she's happy being in the back.
There's something really special about Meimi. She's a decent singer and really good dancer, but there's something more about her that makes you want to watch her. She really seems to enjoy performing, isn't shy at all, and shines to the point of blinding. She is definitely someone to watch out for.
9th Gen
The one thing that bothers me the most about 9th gen is that 3 out of 4 of them are kind of shy or quiet, HOWEVER
Mizuki is a good singer. I've heard it say she's not, but I really think she is. From a Technical standpoint she is as well. I think where people get thrown is she's not really fun to watch, so you're not paying attention to her singing that closely. She really needs to smile or something when she's performing.
Erina is probably the worst singer of 9th (and 10th) Gen, and she's a pretty good dancer, but, like Mizuki, she lacks expression when she's performing.
Riho is amazing. Really. Especially when you put her next to two people who don't really "Perform" she's blowing people out of the water. She's a good singer live (I'm waiting to hear Renai Hunter to see if she's good recorded now) and she's a great performer - she'll smile, glare, her eyes sing the lines with her and that's great. Riho is a veteran and it shows.
Kanon is so underrated is makes me angry

. She's got expression, she performs well, and she sings well. She's also the only one in her gen who started off not shy or quiet. I mean, compared to Riho she's kinda Hurfdurf, but she's definitely second in her gen. I honestly can't believe how much she's improved.