First off, this is fantastic. This is by far the best OSM cycle map website I've come across, so kudos there!
I do however find your choices for PDF generation to be a bit odd. In particular, I don't understand why you post thin strips of the route rather than filling the entire page. Especially for touring, it is useful to get a wider map rather than a load of blank white space on each page. This is the biggest functionality issue I see with this currently.
There are other things which would be nice but are imho less pressing. An overview map on the (mostly blank) title page with rectangle overlays to point you to a page number would be nice, for example. But all in all this is the best tool of this sort I've come across, I'd just prefer to see it become the best tool possible as well.