I watched the entire 2nd season over the weekend whilst introducing a few of my friends to Bakemonogatari as well as playing a lot of Halo Reach.
The 2nd season was decent but as I was watching it, I just felt like this is really really boring, it felt too similar to many other animes. The 2nd season to me didn't really accomplish anything in my eyes, it was slow and had incredibly cheesy lines throughout the series. Especially Touma's so called speeches and I hated the fact that Index would sometimes just bite Touma for the smallest of disagreements. Vento was awesome but her reason for hating "Science" was really shit.
This series and particularly the 2nd season had a lot of cool characters but they weren't given enough air-time or even fleshed out this season.
I really can't give this season of the series much praise, it was disappointing for many reasons but it wasn't horrible. I think I only listened to one of the OPs fully but I skipped them all the time because I didn't think they were any good.
Touma puches too many girls, actually too many male characters punch the crap out of the grils and women in this series. I think the author has some sort of fetish.
My overall opinion was that the 2nd season, "weak, disappointing but cool characters"
. I give the 2nd season a 6/10
, I gave both the 1st season and the Railgun series a 8/10.
However, despite all this disappointment remains hope that a possible 3rd season could make a knock-out victory from what I have read, the story really heats up in the light novel from this point onwards.