So I saw a ton of comments fairly clearly written by or in part by kids who are fans of the show, which is great, but relatively unhelpful if you're curious if this is age appropriate or even remotely educational or enjoyable. So heres a long winded but hopefully helpful review.
As a parent, I am not a fan for many reasons. The most glaring being the dynamic of the character relationship between our leading lady and the titular unicorn. Bluntly, it sucks, the unicorn has zero ZERO boundaries. I know that probably doesn't seem like an issue but if you have kids in that 4-8 range that are developing that sense of appropriate distance in interpersonal situations this will provide a detrimental example with no corrective behaviour from any other participants in the show. The unicorn is literally in your face and the faces of anyone interacting with it.
Secondly this show follows that largely criticised model of 90% conflict and 10% resolution. The characters are under stress for the whole show, it escalates until a breaking point where the title line is dropped 10 seconds later everyone's apologized with heaps of heartwarming faux empathy and we're off to a new adventure in sillyness. Not real healthy unless you want to sit there providing context for your kid so that they build an understanding of how people actually talk about their feelings and progress toward compromise or resolution.
Thirdly the casual throw away lines and gags, seriously just listen to some of the ridiculous things the unicorn drops.
And now for my pettiest gripe: the noise level is insane it uses the same shifts in volume that ad companies use to grab your attention. Dialog dialog dialog BAM SPARKLE BLING LOOK AT ME LOOK AT ME. The voice acting is also intentionally cutesy and babyish - just needlessly annoying.
My kids do like this, the "humor" is consistently at a level they fully grasp, however; compared to almost anything else its just plain annoying.
TLDR just no. You can do better.
