It worked out for Stalin in the long run. By 1945, the Red Army had conquered a big chunk of Finland. And poor Finland, its opposition to Stalin and the Soviet Union forced Finland to ally itself with the Axis powers after June 1941 thereby costing it support from the United Kingdom, France, and the United States.
It worked out OK for Finland, too. They lost 10% of their land but were outside the Iron Curtain. They were also the only country to pay their “ war debt” to USSR of $ 600,000,000 and their WWI debt as well.
Everyone who lived in the captured area left.