The story is based of a Japanese legend or folk tale that I'm unfamiliar with, so I'm unable to comment on how accurate it was or was trying to be. Though I doubt it was the show's main focus. As mentioned before, this is a ecchi fanservice show, so someone who's seen a decent amount of anime will know what that entails, thus I will judge it in the context of a fanservice show.
Story - It's simple, as one would expect from a show like this. Magic peach shards that hold power are scattered across Japan and it's up to our heroine to get them before the bad guys do. Think Inuyasha but minus 200 something episodes and with no romantic drama.
Characters - There's a colorful cast of characters in this show, though we aren't watching for their personalities, but for their bodies. Still though some character interactions will be enjoyable
Art - This is the most important determining factor for a ecchi show. How good it the actual fanservice? Momo Kyun Sword delivers the goods. Large breasts, skimpy clothes, torn clothes, panties, beaches, hot springs, it has it all. If you love a show with sexy women as the main attraction, then this show won't disappoint you.
Other aspects - There's some pretty good comedy in here. The hot spring episode had me rolling. There's also some fighting. Decent enough for a show whose main focus isn't really fighting, though I wouldn't go in expecting much from either of those if you don't care about the fanservice aspect.
Final verdict - Momo Kyun is, and I hate using this word, pretty generic anime. If you skip it, you won't be missing anything you haven't seen before. If you go in with any strong expectations, you'll likely come out unsatisfied. There's really not much to it, but some people enjoy that. If you're not a fan of the genre of ecchi shows, or have had your fill of it, or simply are looking for something with more substance, then this isn't what you're looking for, but If you do like ecchi fanservice shows, or simply large bounching breasts, sexy demons, and naked women, then go ahead and check this out. You'll get your fill of beautiful women, and might find more that you liked than just that.
