I went into Madoka with no expectations. A friend told me to watch it, and I knew nothing more than the meme of QB and that there were girls that could do magic. So I watched the first episode, and I was... well, confused by the shifts of tone, but interested enough to watch more. So I went through the entire series, and liked it a decent bit, though the end left a bitter taste.
The animation was certainly interesting in this series. All characters are fairly simply drawn with what seems like two outlines at points. They were pretty flatly colored, with backgrounds fairly detailed by comparison. When they transform into magical girls there is anime anatomy, which annoyed me. They could have found something to cover the stuff for broadcast, but they went the lazy route. Overall it was decent, but the witch fights were artistic barf. It was as though they took Andy Warhol, told him to make any thing he wanted, and then animated that into the witch mazes. It became more artistic than bizarre about halfway through the series. Comparing the fight with the concert hall setting to the first you can see the improvement.
Characters were all well given distinct personalities by the end, though it could take some time to really get them there. The girl who seems to be based off the common Rei archetype seemed very human by the end, though for a while she seemed quite generic. Other girls were similar cases.
Now onto the plot *spoiler warning*. It started off with the girls observing witch fights, and took a while to find it's feet. Then another magical girl is introduced, and more is discovered about QB and the characters' interactions. It seemed organic and enjoyable enough until the end, which simply went out of control. I think someone watched End of Evangellion before writing it up. Madoka wishes for all witches to not exist in any time, she bares the despair of would-be-witches (which no longer exist?), the world is recreated, she no longer has physical form but is ok with just observing for all eternity, and though there aren't witches the magical girls still have to fight other bad guys. There is still despair resulting of wishes, and you see a main character still dies... Not much changed, she just doesn't exist.
It was an enjoyable series for much of it, though the witchfights were out hard to swallow, and the ending was quite unsatisfying.