Järn is a great, trim and flexible game with a lot of features that haven't been touched upon in the interview above - such as the clan system. And I think it's right to place it in the BRP family - it's not just the D100, there's a lot of (great) ideas inspired by Runequest and Pendragon.
I can see how this thread might look like a plug for the game, but I don't think that's what it is. I think the OP is sincere in saying that he wanted to share an interview looking into the underlying design issues. It is also the case that BRP is historically very dominant in Sweden, so in a way BRP is taken as a base line for what standard RPGs are - much like DnD is internationally - so it is perhaps not surprising that swedish game designers often define their systems in terms of how they differ from baseline BRP.
EDIT: Just realised this is my first post on BRP central! I've been lurking for some years I was sure I had posted before. Anyway - Hi Forum! Brought up on BRP and great fan of almost all of the games you cover/support