Had a quick look at the new TE this morning. The "create all" button creates straight 10 mile long roads for every field and railways for every strat object. These are laid across the existing terrain elevations either N, S, E or W, with the TE seeming to use the direction where there is the least amount of water and/or trying to avoid crossing other fields.
The smooth terrain to grade button levels the road but vastly increases the altitude of the road in places which looks weird. The plow terrain button is more useful, cutting a valley through mountains for the road. The randomise curve button looks to be a very useful time saver, creating a snaking path for the road but based on the existing path. The build clutter mask will likely cull all the trees etc from the roads. I tried it once but it looks like it might take an hour or so to finish so I aborted it. I haven't quite figured out how to make the other properties settings do anything yet.
I figure my workflow will be; create all roads. Then for each field and strat roughly change the path to where I want it to go and also change some roads to rivers. Then hit the random curve button, the plow terrain button and then do some elevation smoothing to get things looking better. Once all the paths are set, hit build clutter mask to get rid of the trees from the routes.