I know I'm kind of late on this, but what the hell. Since I killed myself last season watching anime, and wrote way way too much on it, I think I'll just talk about my first impressions.
Arakawa S2/Index S2
I loved both of the first seasons, so I'm definitely going to continue these. Arakawa was my favorite anime in the Spring, and Index is just plain awesome. I can't wait for more Accelerator/Mini Misaka, as well as Riku/Nino.
Another one from Bones about a boy and his robot- It seems they like this motif. I'm still trying to figure this out, but what I can tell is that everything is extremely colorful and flamboyant, especially the main character, aka the "Galactic Pretty Boy." Every episode so far has been pretty much the exact same battle with the exact same music, with slightly different lead-ups, but it's entertaining to say the least.
Panty and Stocking
This reminds me of an old Nickelodeon Cartoon, packed with non-stop Gainex references, and with a big dollop of vulgarity and double entendre on top. But I would be lying if I said I didn't like it.
Story driven anime? In my fall season? It's more likely than you think. I've heard good things about the Manga form of this, and I have to say it's an interesting concept- I like it.
Shinryaki Ika Musume
Oh Squid Girl, you so crazy. This is just kind of random and funny. It reminds me of Azumanga Daioh. You really can't go wrong here.
My Little Sister Can't be this Cute
I really don't want to write anything else after writing that extremely long title. I think this would be better if it was called "My Little Sister can't be this much of an Otaku," or "My Older Brother Can't be this Understanding." This also spawned a bunch of "My X Can't be this Y" on /a/, which got me a couple times. Hmm I haven't even said anything about the actual anime... Oh ya, the sister has a fang!
And that's my lineup. Just because, here's some of my favorite OP's/ED's for this season.
Star Driver OP- By Aqua Times, who also did "Velonica," the 9th (?) Bleach Op. Good Stuff.
Index Season 2 Op- This shows a ton of cool stuff in the OP which makes me excited for the rest of the season.
Panty and Stocking ED- This has a completely different feel than the one the anime presents. But it's cool and soothing.