Most episodes move slower even than the other children's entertainment on contemporary Swedish state television, which is itself pretty slow compared to more commercial stuff. I assume the pace comes from a desire to have children as young as 4 following along, as well as a desire to be faithful to Lindgren in a 2-cour runtime that's a little too long. Thankfully, much of that runtime is devoted to natural scenery.
“Vargklämman”, the outpost of the fortress that makes it defensible against local lords, is romantically designed here, in keeping with the children's superhuman jumping skills and the kitsch fantasy utility of torches. Other problems with the plotting are inherited from the book. Obviously the route through the forest has to be so economically important that the local lord can afford having his men at arms escort the travellers on it—here in weird but easily animated hexagonal scale armour—while at the same time, it has to make sense for the robbers to steal the travellers' goods. So far so good, but if the robbers ever fence these goods on some kind of market, we never see it. They seem self-sufficient despite not growing a lot of crops or keeping much livestock, and despite having to keep a constant watch.
The implication is that whether the robbers steal food or not, they could live here comfortably as hunters and gatherers even if there were nobody to rob, and the fortress would hardly have been constructed if the valley around it had been less hospitable, yet there is no sign of abandoned settlements elsewhere in the valley, and no sign of settlers from the outside coming to use the ample natural resources. In a more credible version of the story, the robbers would be doing a reasonable amount of animal husbandry and farming, or bring in people to do it for them, and the robbing would be replaced by a more credible early-medieval “road tax” extortion scheme. After all, it is only by force of arms, with the advantage of Vargklämman, that Mattis' band of robbers is able to survive, and somebody has to keep the evidently lucrative route clear.
Credibility would also require more women, whether recruited from outside, joining up spontaneously, or kidnapped from among the travellers. Obviously, Lindgren and Miyazaki prefer the idea of “boyish adventure” over that sort of credibility. The lack of women was probably intended to simplify and dehumanize the two bands as collectives of joyous mayhem and laziness. This version of the story does little to characterize the robbers as individuals, but they are at least visually differentiated. It's a good decision in the book, preserved here, to have the child protagonists reject their way of life in spite of its mostly romantic portrayal.
It's definitely a version for children rather than families. The only contradictory indication is the depth of focus on Mattis as a parent, which will probably interest adults more than children.
The 2D CG backgrounds in nature look nice, whereas the old fortress, lovely in its watercolour overview, is too tidy for credibility in realization. It would have looked better in worse shape, given its near-destruction and deficit of vaulting. It's a wasted opportunity to realize Ian Miller's style of fantasy architecture in animation, à la Wizards (1977). The character design is also pretty good. Lovis in particular looks more headstrong and appropriately powerful—almost an adult Pippi—than in Nyman's portrayal in the live-action version.
I prefer Danielsson's grit and grubbiness over Miyazaki's bright colors. While the cel shading isn't bad in itself, the low polygon counts, choppy movement and slow blinking are pretty dreadful. The quality of the animation is a bottleneck for the quality of the show. It's all too low on visual pleasure, and this time the “vitmossa” looks a bit like ears of corn. Poor visuals is probably a major reason why the show seems to have been poorly received among anime fans. Like the old World Masterpiece stuff, it touches upon anime archetypes and Japanese culture in general quite rarely.
The uncanny valley is used productively in the series' version of harpies, slavers akin to H. P. Lovecraft's mi-go. Their beautiful name, vildvittror, is butchered in its Japanese translation as tori onna, “bird women”. Ronja's encounter with one of these creatures in episode 9 is played up for terror, though it coincides with the most famous comedic scene, where the Swedish voice actors pay homage to the 1984 version. The dub uses Lindgren's charming faux-medieval expressions throughout. The voices of Birk and Mattis are too modern and distanced in their inflection, but the rest is OK. The music is surprisingly good. The opening theme in particular has a catchy Nordic folk-music quality—is that a vevlira?—that I wasn't expecting.