This is technically the last episode of Steins;Gate 0; but actually happens somewhere in the middle of the series. It is worthless to watch. I mean the story isn't bad, and if you need every bit of content you can get from the Steins;Gate characters, sure, give it a watch. But what annoys me is that the red head girl is one of the main focuses in this episode, but after having finished Steins;Gate 0, I don't care for her or like her at all, so I don't want to see more content about her. It also felt like she was being very out of character in this episode.
If you are wondering if you should watch this, I would watch it after finishing Steins;Gate 0 and before watching the other specials, but make sure you watch the other special. Just speed through this if you need to.