Of course catching the keeper off his/her line from the halfway line is a goalkeeper error! That doesn't detract from the goal.
The only way one can succeed in football is to punish your opponent's mistakes. Most players in the women's game and most in the men's game wouldn't have a) seen the opportunity and 2) made the shot. In a video game era, I think people lose sight of how difficult it is to make plays like that happen. Even with the keeper off her line, we're talking about very small margins for error. If I put you at the halfway line, put a keeper on the 18, and tell you, "There you go, lob him," how many would you make out of ten? Now, do it in the context of a match.
It was a killer goal.