Well he did fail in stopping their relegation too.
From what I have seen, he seems to be a decent coach, likes his teams to play football, and is okay at dealing with the media side of things. What he has proved at all of his clubs, however, is that he is pretty useless at spending money to build his own team.
He took wee Tommy's team to 2nd in the SPL (with decent coaching) and then destroyed us when brought in his own personnel. He ran down the Hibs squad in a similar fashion.
It's also the reason he did a decent shift as the Scotland manager, as it was all about making good use of the resources available rather than having spend money to buy players.