Yuri Seijin Naoko-san is a crazy little piece. It's a little hard to describe, but if you're familiar with the "denpa" aesthetic, you'll get this.
STORY: 6
There really isn't any story to be had here. Misuzu's sister left a while back and she's been replaced by a perverted alien who goes by the name of Naoko. Craziness ensues. The focus is obviously on the rapid-fire gags which will be hit or miss. There's one scene in which Misuzu dreams of her older sister which added a nice contrasting touch of nostalgia; it was very well done. Overall, it's all over the place, but that's the point.
ART: 8
It's very well animated. Seeing how it's only half an hour long or so, I would say watch it just for the pictures alone. It got me pumped up. The disconnected feel of the whole thing is both familiar and foreign--it's perfect for setting and motif. It's very denpa-kei.
SOUND: 9
BGM fits. OP and ED are awesome. If you like MOSAIC.WAV, watch it.
CHARACTER: 7
No depth. No development. Still, these characters are a pretty fun bunch and their interactions are lively.
ENJOYMENT: 8
I really liked this. It was very straightforward and it was a fun ride. Despite being little more than a half hour of gags, there's a sense of cohesion and scope. There's a sense of the ephemeral. When it isn't pounding you with excitement, it feels like you're drifting. Naoko-san can be summed up in the OP and ED. If anything, watch those.
OVERALL: 7
If you have time to kill, watch it.