You would think the specials are like 5 minute fillers, with no adding value to the original series at all. However, even though the episodes are super short (with an ED, which takes almost half of the episode), they tell a tiny story or event. Mostly tiny interactions that happen between the characters. What I really loved was that they didn't focus on Jean, but some of the side characters too in every episodes. And as I previously said, this has great dialogue and comedy.
I highly recommend to watch this. If you love the characters, please watch the specials. They bring more dimention and depth into them what was not necessarily seen in the anime series. To me this was healing experience, since I wish there was more ACCA13 content to consume. This just renewed my membership to the fanclub of this series.