I have played 30, I think, PBEMs, half with Allies, half with Axis. Lost 3 of my allied games, lost more than half of my axis games. I'd say its like Allied games: 12-3, Axis games: 6-8. Now it may be that between high skill Axis is better and between med skill Allies are better, but I really think that the game has a very fine balance between the two powers. There can never be a thing as absolute perfect.
My own experience was different. My record with the Allies was something like 7-3, while my record with the Axis was 4-0. But I don't have a serious issue with game balancing. The winner of most games will be the player with the higher skill regardless of which side he plays. If the opponents have equal skill the Axis will probably win if he has high experience, otherwise the Allied player will probably win. My issue is with how the developers have chosen to balance the game.