Putin is, in many ways, among the most dangerous and skilled world leaders. And the most daring one. That none of his actions have been seriously checked by anyone since he came to power surely didn't help either. If Putin had his way, it would not just be Finland, the Baltics and most of Eastern Europe as well.
IMHO, appeasement never worked with people like Putin (or Bush sen. & jun. or Napoleon,...). Thing is that war seems to be the only alternative. And most don't want that. At least not a shooting war against an opponent that can actually shoot back immediately.
Putin is clear that he wants to go back to 1917.
In 1917 Russia ruled in Finland.