When Manaka loses her cellphone with a charm on it from her crush she's obviously distraught, especially when it ends up in the mirror in an abandoned school building. But a girl appears in the mirror and says that she'll return both of them to her but at a price. Do her summer homework of sorts by using the charm to transform 12 times and borrow the power of 12 different djinn to see the world and then write it all down. Manaka accepts and soon realizes that there's a lot she doesn't know about the world and she's not so sure she's ready to seeit.
The answer to my earlier question is that yes, this show gets pretty grim indeed and when I was mentioning it on twitter I had a few people tell me that while they would watch Madoka again they would never watch this again, the whole show, especially with what the ending implies, it just too heartbreaking. But to start at the beginning, while it takes nearly half the show for the story to play it's hand the tone makes itself very clear that this is not a sparkles and sunshine story. Between the music, the lighting, the situations which require Manaka to use her new powers (to escape a guy chasing her and Ichika, seeing a friend get two-timed, watching another friend be unable to deal with the jealousy over the money Manaka's family has, etc), to of course Manaka saying each episode something along the lines of "I had no idea how this would end" the show telegraphs this pretty well. And yet when things start getting bad it's wonderfully done, everything is progressing the same as it has and then suddenly something is different and it's clear that Manaka has not made a agreement with a benign magical gift-giver. Heck, this is the only time I can think of where it's not the magical girl who chooses to transform and use her powers but the powers that choose to transform the girl and that itself is a darker take.
Moving away from "this series is grimdark and will break your heart" for a moment, one thing that any story has to sell the viewer/reader on is "why did this particular story happen to this particular character and how does that fit into this particular setting?" and it can be really hard to justify the circumstances in a magical girl show in a non-magical setting. When all is said and done I think this show pulled off that plausibility better than almost any other magical girl shows out there, it simply wouldn't have worked if Manaka wasn't as young as she was and if the world wasn't as mundane as ours is, the overall theme would have been lost.
As for the production values, it's an older show so it's letter-boxed and the quality wasn't HD but honestly what stuck out to me more was the rather unexpected fanservice. Like I mentioned earlier, this show was created for a late night slot watched by a lot of male (presumably straight) otaku and I was, unintentionally I think, skeeved out by quite a few of the shots. Some of Manaka's magical girl outfits were a bit scandalous for a middle schooler as well, I did like that she had a new one each week (and that they put the original design in the credits each week) but i've heard that some were by hentai artists and I completely believe it! And I wavered back and forth on my opinion of the OP and ED, probably because the OP is cheerful and upbeat while the ED is a much sadder melody. They both do fit the show just different parts of it, too bad there wasn't a way to just air one or the other depending on the mood of the episode but I can think of very few shows that eschew the usual op/ed conventions (Penguindrum did swap out a few different ED songs in it's run and then sometimes you get shows like Sunday Without God where the songs always bleed into the actual episode or From the New World where they completely cut out the opening but that's all rather unusual).
So in the end, do I recommend this show? Sure! It's different and really holds together in the end and is one of the rare shows where I can say it doesn't end on a particularly happy or unhappy note. Admittedly the 13th episode, and OVA, helps out with that (don't worry, it's also on hulu) and I can see myself owning it on DVD someday, just not rewatching it anytime soon. It's a 3.5 or 4 out of 5 folks, great, not perfect, but closer to it than a lot of shows get.