Back Arrow starts as a run-of-the-mill fantasy adventure with some very basic comedy sprinkled in that seems to offer nothing new, but if you keep going on, the zany stuff starts to show up. Story-wise, it starts broadening really soon, and going wackier and wackier the more it goes. It has that bit of a Gurren Lagann feel to it in that aspect, and its story beats certainly end up going "there" in the end, which is a good thing, as it feels satisfying, and not hair pulled as many other recent stories that tried to pull something similar. In short, it's a funwatch. It's not a masterpiece in any sense, but it's got pretty solid foundations and built from them in such a way that can bring quite a bit of enjoyment if you're prepared to suspend your disbelief and give in to the craziness.