I've been pretty excited to read this, having faithfully followed the series up to this point. The series is still far from over but this is where we start getting the clues towards who or what is causing this.
I really enjoyed this glimpse into Rina's life. Up until this point the manga has portrayed her as a mostly happy-go-lucky and easygoing girl, but this arc really dispels that aspect of her. This Rina is a worrywart and is just as capable of doing horrible things as her friends were in their arcs. She's a dark and tormented character, but we really shouldn't expect any less from any of the inhabitants of Hinamizawa.
The artwork in this is nice and as always, I loved it. I'm pretty easygoing as far as artwork goes and I'm a sucker for anything Rina related, so it's pretty obvious that this volume would be something I liked. This is an absolute must-buy for fans of the series.
On a side note, if you're someone who has just decided to pick up the series and is looking at the various volumes marked "1" for the Higurashi series, be aware that this is actually volume 15 and you will absolutely have to start at the true volume one, which is in the Abducted by Demons arc.