The iDOLM@STER: 765 Pro to Iu Monogatari, which is also known as the Idolmaster Special, is a 26 minute OVA of sorts that was released with the iDOLM@STER Blu-ray disc. It is essentially a compilation of short, quick stories revolving around everybody within 765 Productions. If you have a favorite character from the original Idolmaster series, don't worry; there is a high chance that they're in this episode somewhere. (Yes, even the members from Jupiter are in this episode.)
The stories themselves maybe short and presented in a slice-of-life kind of way, but they are still very humorous. You'll be able to dig a little deeper
into the more trivial aspects of the idols' daily lives in a way that is much different from the original series. However, if you're looking for some intense drama (as with 961 Pro in the original series), character development, or anything of that sort, unfortunately, you won't find it here at all. This is just one episode after all.
The sound, as with the original Idolmaster series, is arguably the strongest point of this episode. There is plenty of music presented throughout the Idolmaster Special. It never ceases to amaze me the amount of effort that people put into the creation of these songs.
The art is very similar to that of the original series too. More importantly, there are no glaring inconsistencies. All of the characters, settings, and objects all share the same style of artwork. Furthermore, everything moves quite fluidly as a whole.
Overall, the Idolmaster Special was definitely funny and worthwhile, but don't expect anything overly meaningful from it.