As someone in a similar situation (minus the whole brother complex!), I can say that it touched my soul a little, and made me nod with a knowing feeling, "that's exactly how it is", at the suffering of the little sister in the story. That's why I enjoyed it as much as I did, likewise anyone who has a crush on someone who is seemingly out of their league will appreciate this one-shot.
But despite this, viewed critically this manga will not stand up to much. The art is very much what you would expect from a clichéd shojo manga, with little flare to it, and many panels are just plain screentones. There is little attention given to detail in the drawing or the plot, this is almost a concept or a girl's thoughts as she is lost in fantasy rather than a story.
However, I'll go easy on it as it is so very short (and rather cute), and settle for a 5. There are most definitely better shojo one-shots out there, but you could do worse than a timid little romance between a young girl and her brother.
