Well although I've lived here nearly 6 years I've still seen very little of Honshu, spent most of my time here in Hokkaido. Hokkaido is a very beautiful place. If you love the outdoors and nature it's hard to beat but it does lack the more ancient Japanese cultural stuff you find on Honshu as the Japanese didn't settle up here in Hokkaido until much more recently. It is an incredibly beautiful place though and I'd recommend to anyone to come here. We actually get quite a lot of people from Singapore and Hong Kong come to the resort I work at to escape the heat and humidity of SE Asia during the summer months. Lots of hot springs in the region and lots of outdoor activities.
My favourite season up here is the autumn. Nice cool nights, mild days and incredible colour in all the forests with the first dustings of snow on the mountain peaks. Simply amazing.