blizzid on 15 March 2009
From http://www.halowars.com/stats/globalstats.aspx:
UNSC Win Percentage - 49.33% (1,644,189 Wins / 3,332,804 Uses)
Covenant Win Percentage - 51.02% (861,074 Wins / 1,687,636 Uses)
Looks pretty balanced to me. Of course stats like that aren't useful for determining exact balance, particularly when it comes to skilled play. However, if one side was completely underpowered like you suggest, I'd expect the win percentages to reflect it.
