Review of A Certain Magical Index

Overall, this is a waste of what could have been an amazing story. If you read the other reviews you will quickly see the pattern that though the premise and idea are great, the execution was off. Most of the cast is static and half the story is terrible. It tries to do two genres (magic and science), but fails to blend them and only does the science side any good. It does have some highlights, though. I would watch it, at least the beginning and most of the science arcs as these are the best parts with the most development. The sisters arc introduces the twobest characters in the series (they are even ranked this way on Animelist), Misaka and Accelerator. If you watch the Railgun S spin-off, you'll see this arc even more in depth. This is the best arc with the greatest and most original plot and fight scenes. It is the diamond in a series full of coal.
The main protagonist is your normal idiot that rarely understands the situation he is in and tries to be a bad-ass, but fails fairly often.
The art is phenomenal, I even really enjoyed some of the architecture in the city (something that I normally do not notice in anime). Great music.
So overall, I suggest watching the science arcs and ignoring the magic ones, just as the anime does.