Pretty neat!

I did see a problem with stairs — not sure if algorithm does not take into consideration or if data is not properly marked up in OpenStreetMap, but locally, it recommended a route goong over two long sets of stairs: one of them being practically a goat trail I would recommend against running on, but careful trodding is ok. The other stairs are long and wide, so probably not perfect for running (hard to figure out your stride), but ok. I wonder if elevation rate could be taken into account, which would probably exclude the goat trail one.