The basic structure of this 12-episode fall 2009 series is a little unusual: it is a harem romantic comedy whose defining gimmick – that the hero, who is already allergic to cats, has become cursed by a Cat God and must do good deeds for cats to survive it – only peripherally figures into its harem aspect. Although this does result in some amusing scenes where cats comment on Jyunpei's relationship foibles, it also often makes for an awkward balance, with the two main aspects distinct enough from each other that the series alternates between Harem Mode and Cat Mode. A more effective route would have been to smoothly integrate the two elements, but that would have required some actual effort on the part of the series' writing and composition and neither seems inclined to give that here.

Actually, that is not entirely fair, as the series does at least try to mix in some slightly more original elements. One of the potential love interests is boyish in appearance as well as behavior, another girl is interested in Jyunpei specifically because she has a fetish for misfortune, a spirit-fighting magical girl element pops up unexpectedly in a late episode (and, unlike with other recent series, this is not something on TV within the series), and the “childhood friend” girl is initially both at odds with the main character and an extreme gal type. The latter two elements only last for a couple of episodes, though, and the relationship hijinks otherwise play out with stalwart regularity. Most of the scenes anyone familiar with this subgenre would expect – the cutesy scenes where the male lead and his main love interest are too immature to be able to express their feelings towards one another without extreme embarrassment and constantly interruptions, one of the girls acting abusively towards the guy on a regular basis and getting away with it, assorted schemes by another character to get the male lead and his main squeeze together, the central guy turning out to be a nice guy towards pretty much everyone, accidental groping and peeping, misunderstandings about intentions, and of course the obligatory hot springs scenes – are here, and the series tosses in scenes of the slavishly loyal/protective servants of the rich girl devoutly attempting to execute her ridiculous schemes for good measure.

All of that could still work if the harem aspect did not suffer from a distinct lack of exceptionality. This series would have made a more favorable impression had it come out in the early 2000s, but recent developments on the harem front have left it outclassed. Sure, it still has its fan service, cutesy elements, and multiple-girls-falling-over-one-guy shtick, and Jyunpei is at least not a total loser, but the most successful recent harem series are some combination of more clever, more zany, and/or more extreme in their fan service elements and general raunchiness. The Cat Mode elements do help, especially the goofy training sequence and the way the cat's voice and attitude change in the before/after contrast, but even with them this series is nowhere near as funny or sexy as, say, To Love-Ru. Milder harem series like this one just can't cut it anymore.

The artistry and animation are also nothing special. Character designs provide a good variety of physical types for the girls, including a strong, simple charm for Mizuno, although aside from the one episode where Kanako uses her manba look (i.e. a very distinctive combination of make-up, tanning, and hair coloring little-seen in the WEST. beyond anime conventions – see this link for examples), only Nagi's design deviates at all from standard harem archetypes. Cats tend to get more cartoonish looks, although AIC did at least make an effort to cover a wide variety of cat looks. Character rendering quality is very ordinary, too, with a heavy dependence on superdeformed looks for comedy bits. The animation quality strongly suggests limited time and budget.

On the plus side, the musical score does everything it can to enhance the comedic mood of the series and is fairly effective at it, with a good sense of timing and a deft touch evident throughout the humorous bits. It is bland elsewhere, however. Opener “Nyandaful” is suitably light, cheery, and energetic, while closer “Strawberry ~Amaku Setsunai Namida~” is a yawner.

Sentai Filmworks presents these twelve episodes on two disks in a single case. The set has no dub and includes only clean opener and closer on the second disk as true Extras. Like many of their other recent releases, though, it does have some on-screen explanatory notes as they come up in the episode.

Nyan Koi! ends without the main premise resolved and even outright says that it is hoping for a second season so that it can continue, though as of this writing no announcement to that effect has been made. It is certainly capable of being funny and sexy and does have its moments, and for some that and the cat gimmick may be enough. There are definitely funnier, sexier, and better-looking recent series out there even within this subgenre, however.