Because of the long distances the locals drive like lunatics in Lapland and the roads aren't always that good. If you ride long distances in Lapland, you'll be riding long stretches with nothing special to see. Forests are just like in the south but with smaller trees. Population in Lapland is very sparse outside a few small towns and holiday resorts. No services, no sights to see. Of course, if you like jänkä and what if has to offer (animal and plant life etc.), that's different.
RE: Ultra Long-Distance Cycling