Before I talk about the plot, let me just say that, despite these flaws (which aren't so minor as to say "but these are just little issues I had with it!), the plotlines in this show are really, really enjoyable, and definitely give you deep questions to ponder after watching.
The story was craaazy interesting, mostly because there are so many parts to it. Don't like one character's plotline? Wait two minutes and you'll be on to the next one. But at the same time, the mish-mash of so many plots kind of made it lose its coherency. If you asked me what the plot was, I couldn't tell you, because it can't be put into words. And while that's not necessarily a negative, for me it was a bit, just because it made the show seem a bit messy at times. And while that messiness can keep it interesting, it can also make it hard to get invested in sometimes. I know several people who dropped it because of that. But at least each of the storylines had its own interesting resolution.
But at the same time, there was a lot that was left unexplained. There's a random magical sword thrown in with no explanation, there's IM conversations that you aren't meant to understand until the n-teenth episode, and don't forget the arbitrary, random piece of Celtic mythology thrown in with ZERO explanation (or much resolution, but I guess/hope that's what the second season is for). These things are put in to give the story substance, but their lack of explanation makes it that much harder to believe.
The characters are all interesting in their own way, but it's evident that when it came to character writing, the writers went for breadth, not depth. (As is evident by the sheer number of characters.) But that's okay, because it's the character interactions that truly make the character aspect of this show so great.
Also, let me just say how much I loved the ED/ODs. The first OD in particular is just a truly awesome song, one that transcends anime music stereotypes, and the rest of the songs sound strikingly similar to West Coast music. The art in each of these is also really cool (more props to the first OD), and the art throughout the whole show is also great, particularly with regard to Celty.
Overall, I'd say that it takes a while of watching this show to understand why everyone says it's so genius. And if you ever feel like dropping it, please please please pull through!
