This is a rare occasion where I find myself actually preferring the spinoff over the original. In this version you don't have the mandated minutes-long scene every episode where Toma Kamijo lectures the villain of the week on how what they're doing is wrong, while you're rolling your eyes and wishing he would just shut up.
The tradeoff is Kuroko Shirai freaking out and screaming at you about once or twice an episode, and the drama is a bunch of high school girls instead of a 14-year-old boy whining about morality. Railgun tends to be more direct and less philosophical, as the titular character usually just blasts stuff instead of talking her enemies to death...but that's understandable given their difference in powers.
There's some plot problems later on where you wonder where the heck Railgun's parents are, that she's being asked to make ethical decisions for herself as an 8-year-old in flashbacks, too, but maybe that's just an anime thing? The plot arc enemies they fight can also strain suspension of disbelief at times (especially considering this is supposed to be the more scientific and less fantasy of the two shows), but if you've watched Index already, that's old hat.
Still a fun show if you're willing to wobble over and back across that line of whether you should take it halfway seriously, or just sit back and enjoy the nonsense.
Disclaimer: Oh, apparently there's a third season now. I've only seen the first 2 so far.
