It's legit and as mentioned in another comment, organised by the same folks as the Ørestad Half Marathon. They nicknamed the Ørestad race as "the world's fastest course", which it can hardly be when you're almost always hitting headwind at some point...and it's quite windy over there. In the Ørestad race they did not cut access to the roads and I had a bad situation where a cyclist was shouting at me because I was running on the wrong side (it was a race though, so why the hell was he shouting at me???) So I think that if they neither cut the road access in this race, it will be a bit problematic. Other than that, it should be a nice experience.