Thanks for this feedback.
I'm pleased to say that you can already highlight hilliness on a route map - see the following guide on How to show gradients on a route map.
We've added the other suggestion regarding surface types to our Feature Requests list (number 101) where people can vote for this.
It would be nice to see with a color if a part of the route is paved or unpaved (when using mixed mode). Also a percentage paved or unpaved would be a nice feature.
More aadvanced would be a feature to see if a route goes up- or downhill.
With kind regards,