Looking into this after Denpa, I'm a bit disappointed. Both were light novels by the same author, and are marginally connected. Characters have family ties, for instance. They were animated by different teams at the same studio, with the newer OVA being released as part of the TV series' limited edition DVDs.
Kurenai already had the schoolkids-with-dark-aspects, but the main attraction was a child who talked like her own aristocratic grandmother. People dig that. Her voice actress is doing a pretty good job, but like most of the cast she's not well known, and for a reason. People may like the more natural sound that often comes with this.
After enduring the opening I much enjoyed two episodes (the ending is better) but slowed down during three and four. Stories that rely on stupidity or lack of communication irritate me immensly, even knowing that they're less improbable in Japan. As an aside, I recently watched City of Ember, and already hated the story when three minutes in the MacGuffin gets lost in the silliest way possible...
The weirdest part is how the director chose to spend his money. They went to some lengths to get the car right, even sampled the engine of a Quattroporte, but then processed it to sound like the starter of a Micra. The animation is generally poor, heads look like mannequins with loose wigs, and the fight coreogrpahy isn't gritty but crappy. Then we're treated to gratuitous shots of loli hair flying in slow motion.
The backgrounds are nicely painted, and you get a hint of the atmosphere that Denpa has. Unfortunatly the sharper and less dimensional characters look out of place sometimes, like 2D sprites in the 3D scene of an old videogame. Only with very lively faces. Those reminded me of less commercial animation, often distorted but good at conveying emotion.
All in all an interesting way to assemble three of five stars, a rating where I'd normally stall. But the series has character, and that's promising.