Steins;Gate: The IBM Ad is a series of four four-ish minute long OVAs created as a collaboration with IBM to explain the impact their Cognitive Computing (AKA advanced weak AI) could have on daily life. The shorts follow the Gadget Lab some time after the OVA episode as they relax and live normal lives together. Mayuri brings in a Upa she brought that have Cognitive Computing on board and they proceed to use it for a variety of mundane yet entertaining things.
The story is weak, but it doesn't do anything to hurt Steins;Gate's great plot. Its place in the timeline is clear, but its canonicity, or lack-there-of, is also clear. Each of the stories are perfectly coherent slice of life fair. The writing is funny and there's even one touching Okabe-Kurise moment that gets pulled off perfectly.
Art is fine, the great art style of Steins;Gate returns, but the budget is clearly a few pegs down. Expect cross-eyed Kurisu, off-model Mayuri, and rapidly expanding & deflating Daru, but don't expect outright ugly.
Sound is... okay. The voice actors all come back and do a fantastic job, but as far as music goes... I legitimately can't remember. As of writing this, a mere ten minutes after watching the shorts, I cannot describe what the music was like. I just pulled up an episode, and it seems to be mostly stereotypical background bleep-bloops. Nothing offensive to the ears, but it it instantly forgettable.
Characters are spot on. After watching the movie and seeing how badly White Fox's writers can butcher the characters, they are absolutely spot on with them this time. The OkabexKurisu moments play out exactly like they should, Mayuri is as adorably spacey as she should be, Daru is an unrepentant pervert, and all is well.
Overall this is a perfectly acceptable little OVA series. Don't expect it to rock your world or anything, but if you want some bite-sized Steins;Gate, there's a lot worse ways to burn fifteen minutes.