It's hard to settle on a single rating for this volume. The one-shots run the gammut from pointless to ridiculously cute.
"Sagashimono" is the one-shot that goes with the synopsis posted here. It's a rather plain and somewhat dull one-shot. The premise seemed forced and didn't really interest me much. Like deathbypenguin said, this one-shot was a bit like oatmeal. Bland. Flavorless.
"Seeds of Worry" is an improvement over the previous one-shot, but still suffers from not-enough-going-on. Also, the beginning was confusing. The girl and her best friend look too similar and I had to figure out which was which and why it was important. I'm still not entirely sure why it was important, though. I think this is a cute idea, but clumsily done.
"Kisenai Toge" is a mini-manga. There's hardly anything to it and it feels cheap to even call it a one-shot or review it as one. I hate mini-manga. Most mangaka can't successfully tell a story in only a handful of pages.
"Sissou Beat" is where things do a complete 180 and it becomes hard to review the work as a complete volume. This one-shot is really, really good. It's cute and silly and made me laugh in a few places. The heroine is certifiably insane, but likable for that very reason. The male lead has the patience of a saint and is laughably stoic at the perfect times. If I was reviewing this one-shot alone, I would easily give it a 9. Sadly, it feels out of place in this volume, where everything else is relatively mediocre.
"The Blue Paper Plane" is another mini-manga. This one is better than the other one, but still doesn't come close to telling a complete story. Still, it's actually cute and illustrates a cute moment in what might be a cute story, were it actually a story and not just a mini-manga moment.
In all, the volume is worth checking out for "Sissou Beat" alone. You also might enjoy "The Blue Paper Plane" and "Seeds of Worry" - but no guarantees there. Like my title says... This volume is really hit or miss.