Story: Basically, Higurashi Kai: Ura Higu is a bunch of 30-second shorts what are just meant to be little jokes relating to different subjects throughout the series.
Sadly, I think it failed at this. I only found about 1 or 2 out of these 24 shorts mildly funny, and they weren't brilliantly funny, just a-small-smile-on-your-face funny. I didn't really get that many of them, but I think to really find them funny you have to be into Japanese cultue and lots of general japanese things, so that could be why I didn't get their funniness.
Animation: The animation was actually pretty good, just like the original Higurashi Kai, thats about the only good point to this series though.
Sound: A few little jingles were used in this, but thats it.
Characters: Of course, as to be expected, no character development can really take place in the space of 30-seconds- nothing much really did happen at all with the characters, they just had short conversations.
Overall: Watch this is you like Higurashi and have nothing else to do with your time, but I wouldn't recommend this series. It isn't that humourous and the jokes are hard to understand.
It really feels pointless to write a review for 'Ura Higu' but since there's very little information about it here on Anime-Planet I thought I'd just explain what it is.
Ura Higu consists of 24 very short extras' (ranging from 25 to about 50 seconds) that have not officially been English subbed; however they are available on the internet. I'm not sure of their origin but most likely they can be found on The Japanese 'Higurashi No Naku Koro Ni Kai' box set. 'Kai' has yet to be released outside of Japan due to controversies involving a 16 year old girl killing her father, so as of now the only way of seeing these extras is using the internet, unless you know Japanese good enough to own the Japanese box set.
These extras' seem sort of pointless, but then again they are extras' and are not meant to contribute anything to the story. Extra number 1 features a grown-up Rena advising Oiishi about insurance policies. That was kind of amusing, but after that there's really not much to laugh about.
Another example includes Rena trying to stop her skirt from flying up, as she's not wearing any underwear. And another extra has Rika grabbing Mion's breasts with an almost obsessed facial expression.
Rating the story, characters, sound etc. would feel kind of silly as there's no real point to this. However, I give it an overall rating of 3. It's pointless and rarely amusing, but if you liked 'Higurashi No Naku Koro Ni' then maybe (just maybe) you'll be able to find something of value.