Note: the following comes from a video review, links on my profile page.
Narutaru is about a sort of cycle of life, but it comes in fragments; at times shows it, other instances explicitly states it and questions affairs. It seems uneven on average, and often it is difficult to reconcile specific incidents to the story overall; some apparently more relevant than others, although in the end it seems they may have been connected - they still seem not coalesced ultimately. This is likely due to only half the manga being adapted.
Second episode had a few seconds of an existential sort of connection, but it did not pursue this further beyond the character's personal insecurities. The third episode had an Evangelion-like hint as the second one had (which is apt considering Mohiro Kitoh went on to design for 2.0), but yet again it did not expand more than this, for some reason (also at the end there was a parallel test of will). Similarly, like with Angels in that anime, the creatures here are called dragon's children, but other than this there was little else, besides the interactions between them and the characters themselves, whereas Angels were expounded upon at length in nearly every episode. The army was also introduced at one point, as it was with NGE, but the conflicts did not seem as epic or as precarious as they were with Angels, perhaps because of the abstract nature of these dragon's children, in comparison; it was not as obvious as in NGE, and also the SDF simply disappears in Narutaru without much of an explanation (this also happens with at least one motherly figure and some of the earlier characters later on) and barely any resolutions were forthcoming about any of several of the story's knots.
It presents undiluted despair (not unlike Bokurano, by the same mangaka) and yet it doesn't seem to have meaning beyond that which is shown at any one time, unlike Bokurano which does build an all-encompassing universe where angst has a clear reason and the future is uncertain, despite being animated. It talks about moral issues, but in the end it does not seem to quite fit them in perfectly with the narrative like Parasyte did. In terms of where it fits with other narratives about oni, though, in just one arc it seems to show how people can be either internally destructive, guilt-ridden, self-blaming; or angry, and externally focused (also the factor of influence), and that the idea of an oni 'projection' - as most other anime about such mythological creatures imply, as in Shuten-doji, oni are anger manifest, essentially, beasts that are objectively identified as such, but in reality are the equivalent of invulnerable humans rampaging. How and if they're distinct from the 'dragon's children', though, the anime does not say; they could be a range of psychological states, e.g. the protagonist and her nearly unending optimism, which the animation generally shrouds itself in as its veneer, and the manga likely goes into much further detail about this, but the anime does not really connect any dots even at the end. While, on the other hand, Paranoia Agent three years later is not explicitly transparent about its questions' answers and expects viewers to think, Narutaru seemingly has gaps not intentionally for the same reason (except perhaps at two points where hair is used symbolically).
What it does well is in setting up the stage in the first episode, except most of the others then did not seem to ascend and fulfil a certain promise, apart from the tenth, which stands on its own and adopts the first episode's disjointed sort of logical artistry to an interesting catharsis. As such, unless all the episodes were more cohesively connected into an over-arching world, it would have done better if each was independent like the tenth, so as to not necessarily have to resolve plot holes left over due to the inevitable short time. In a way, the whole of the anime is like how the 'knife' dragon user acted to a potentially blossoming flower plucked out too early. Unlike Digimon, although more childish, spawning hundreds of episodes; even Tamers, which Chiaki wrote for at the beginning and end, just like for this series, had ample time to establish itself a certain mythology based around the Zodiac, whereas Narutaru got a foundation, but then barely solidified its narrative's upper structure, metaphorically. It concentrated mainly on vengeance, and mostly ignored the dragons' origins, which could have likely imbued it with interest.
The ending is more abstract than the episodes themselves try to be, besides perhaps the aforementioned couple, and the opening deceptively playful, but there could have been more star-gazing, and while the weather played a minor part in the story it had potential for more, if these dragons truly were as potent. Food was also another quality that might have been absent from Bokurano in comparison, and it provided a reprieve from the despair, but ultimately, as a kind of 'glue', the narrative is still difficult to hold together.
In short, the adaptation of the rest of the manga would have made much difference, otherwise the anime could have tackled stand-alone, perhaps unique situations, as with the above average tenth episode, and this would have improved upon the cohesiveness aspect. Kino's Journey did this, but also managed to connect slightly various episodes. Narutaru had its interesting moments, but they were few and far between.
