How disasterous was it? Just ask the man who was in a position to know - OBL himself.
OBL "fatwa" : "...However, when tens of your solders were killed in minor battles and one American Pilot was dragged in the streets of Mogadishu you left the area carrying disappointment, humiliation, defeat and your dead with you. Clinton appeared in front of the whole world threatening and promising revenge , but these threats were merely a preparation for withdrawal. You have been disgraced by Allah and you withdrew; the extent of your impotence and weaknesses became very clear. It was a pleasure for the ‘heart’ of every Muslim and a remedy to the ‘chests’ of believing nations to see you defeated in the three Islamic cities of Beirut , Aden and Mogadishu...I'll say it again - A few decades in the marines doesn't mean you know anything about geopolitics. Indeed, the fact that he only rose to the level of colonel during that time is a fair indication that he didn't have "the right stuff" to play on a geopoltical stage. Retiring as a colonel is what happens to the guys who are passed over for promotion several times in a row. They don't get passed over because they're exceptional, they get passed over because they're mediocre talents.