The Other Darrin: So far, the anime is using an entirely different cast from the Drama CD.
Sleeper Hit: No one was expecting Ars Nova, which aired during the Fall 2013 Anime season and whose source manga filled a rather niche readership, to become one of the more acclaimed adaptations during said season. Even better, in the following year, famed magazine Newtype has handed out fan-selected prizes to various shows, and among them Ars Nova won several top prizes (as well as many runner ups), lining it up along hit shows like Kill la Killnote For reference, here's a list of awards handed out after Newtype's web voting.
What Could Have Been: When Discotek Media announced their home video release of the series, they already had a set release date for late 2015 and were only planning a DVD release. They eventually announced that the release would be delayed to a further unknown date, but that they were now planning to release it in a DVD and Blu-Ray combo pack.