It certainly damaged them. They lost their host country, many of their training camps and were forced to flee to Pakistan where the US (or more probably Pakistani intelligence) has had some success in capturing some of their enemies. It clearly wasn't a decisive blow, but its too early to say whether this has advanced Al-Quaida's program. A huge part of Al-Quaida's power came from their mystique and seeming invulnerability. Now that they have lost this, they may have lost much of their appeal to the disaffected youth of the Middle East. Nobody much wants to join a gang of losers.