It was a really good call, something the referee commity needed after Graham Poll's incompetence.
I do hope you're being sarcastic, as there is no way you could consider that to be a good call. First of all, it was a deflection off of a Korean player, not a korean player losing possession so Frei WAS offsides. Second, both sides stopped playing (the swiss only for an instant) when they saw the flag raised, even Frei. You can't call a goal in this instance because a referee interfered with play. It's the same as letting play continue when a fan runs onto the field. It's as they say, Players win games, Coaches lose games, and Refs ruin games. Truly one of the biggest blunders of the cup.