Wouldn't have made a lot of difference outside of Europe (assume, just to keep things manageable, that Japan didn't go on to conquer Asia and Australia - that's a harder one to predict). In the short term, would have been terrible for jews, gays, Romas, and slavs, and Europe would have had an even more difficult time recovering economically. But the fascist system would have collapsed quickly without the promise of a 'great big enemy' and instant economic fixes to sustain it. Even by the time the war started, the fascists had lost a lot of popularity, with assassination attempts starting up.
The biggest change would be that you'd have a sustained period of communism following the demise of fascism. Under the conditions of nazi Germany, the moderate left couldn't organise, whereas the circumstances actually favoured the 'underground network' methods of the contemporaneous communist movements. Communism would have filled the hole for at least a few deacdes - hard to say whether that would have ended up going Stalinist, or whether without the threat of a cold war, you'd have seen something closer to China. Ultimately, however, the systems would revert to match the national cultures, with socialist countries in the prosperous north, a centrist England, France and Germany, and capitalist southern europe, pretty much as they are now.