Solens Rötter also has elements of other genres of metal. There are some traditional metal guitar riffs and melodies along with more forbidding black metal touches. It's a nice combination of the warmness of folk metal and the coldness of black metal.
The lyrics are entirely in the band's native Swedish, and Vintersorg's vocals are a combination of melodic singing and black metal rasps. On really extreme albums it doesn't really matter what language the lyrics are in because you can't understand them anyway. But with an album like this with a lot of melodic singing, the language barrier is noticeable.
Still, whether you understand Swedish or not Solens Rötter is enjoyable. It's a diverse, complex, progressive and entertaining album.