I'd give it a 9/10, but not for the reason you'd think.
I found the plot, the character design, and the music to all be top notch. It was an interesting twist on Magical Girls and threw out the sunshine and rainbows model. Since the show focused more on emotional conflict, the action was much more limited, but I thought it was done well in such a way to not make the abilities and magic over used.
I actually liked the ending, though I'm tempted to check out the manga to see if it had a different one. I'm not really sure what I was expecting as a conclusion, but what I can say for certain is that the ending was well thought out (FIST OF COURAGE!) and that alone is valuable. I found that her wish was not only grand, but it still exemplified Madoka's qualities. The wish also wasn't so easy to grant since it required a huge sacrifice as well. Overall, I loved the show and while I have no clue what was going on in the last 30 seconds, I can only hope it's a hint of some sort of sequel (doubtful, but I can hope).
When I finished the show though, I found myself curious about the laws of the new world- guess I'll have to put my imagination to work.
I had one problem with the show and it's really the only reason I wouldn't give it 10/10: the animation. I liked the character designs and I loved how the world appeared, but every time there was a close up of someone's face, there were these thick lines outlining the shape. I don't know if they were actually going for that style, but to me it just looked like laziness. While this is a minor issue, it was there EVERY ******* TIME! It might be silly, but it really got to me after a while and so, because of the appearance of lazy animation, the show loses a point.