Route: Well signposted, plenty of other riders. Best map is the blue spiral bound series by Verlag Esterbauer.
Roads: Lots of dead straight concrete road alongside high dykes and flat marshland with sheep.
Much of the Danish section is on unpaved/gravel roads but they are easy to ride.
Dont miss: Trips out to the islands, Texel, Vleiland, Sylt.
Do Miss: some of the concrete straight roads by visiting old towns inland, esp in Germany.
Some of the large bays and rivers can by crossed with ferries.
Accomodation. There are some hostels but you will need a tent most of the time. Plenty of campsites of various grades from primitive to fully commercial marked on the route map.
In Denmark there are lots of wild campsites not marked on the route guide. You find these using a guide book
avaialble from Danish tourist information shop (in Tonder). Min facilities are a water tap and a drop toilet, sometimes a wooden shelter, farmyard sites often have hot water showers and some have kitchens ! Cost is from 0 to 3 euros.
I experienced one day of horizontal rain coming off the sea in Denmark. It is more fun than it sounds.
Any 2-3 person tent will be sufficient. Cooking kit will give you more freedom and less cost. I saw people with trailers full of 15kg gas bottles and 2-burner stoves which in my opinion is overkill.
You can use any kind of bike, whatever you have.