I watched the full first season during Christmas break. I spent a lot of time wondering why I was watching it.
It moves incredibly slow, amazingly slow. It's more of a meditative movie than an adventure. I eventually was able to predict the order we'd see the locations as she walked through the forest, because they'd show each one of them every time she left the fort.
The biggest concern for me was the characters. There weren't any. There were 8 Robbers in Mattis' group with unnamed counter-parts in Borka's gang. But 90% of the time they were all just grunting and interchangable extras. (This include Borka and Undis.) They definitely didn't have any sort of arch. Mattis and Lovis (Ronja's parents) were at least distinct characters, but once again, they weren't developed, and were more caricatures than characters.
The only actual character in the show was Ronja. However, Ronja was absolutely captivating. Her spirit and courage made you admire her, but her wonder and depth of caring made you love her. Even Birk, an exceptionally mature, confident, and patient friend wasn't deep enough as a character to make you continue watching.
So basically, I sat through 12 hours of nature scenes and pointless grunting and howling from the ensemble just so I could spend more time with Ronja herself. I'm not sure the show was worth it, but I definitely enjoyed Ronja.