I have heard that burning fresh wood can cause soot and resin problems in chimneys/fires and there is a fire hazard in open fires that fresh wood would( :) ) pop and spit and could toss embers out and set fires but obviously not a severe problem in a stove. I know that fresh wood is not as efficient, heatwise, as "seasoned wood" it just needs the time to dry out/cure. If you are desperate for heat you could use fresh wood short term but make sure your chimney gets checked/cleaned regularly.
Bruixot