Good special, not as great as the anime but definately somewhat on-par with the absurdity. It's basically just an episode centered around Urabe getting captured my some spirtits of some sort and her BF has to find the right way to get her free. Definately nonsenical, but mainly meant to be supplimental to the series and not something one could enjoy by itself. I tend to think of it as a secret bonus episode to the series rather than an OVA.
The only iffy thing I can think of is that there is no dub for this, and that it's exclusive to the Japan Volume 9's Collector's Edition. AKA, it's mean't to be a bonus tie-in to the manga if one wanted to purchase it.