As much as VDL is a controversial character in Germany (and in the German speaking world, judging by the reactions of ETribbers), she is pretty much unknown in France. I've read about mismanagement of the Ministry of Defense and the derelict state on the Bundeswehr, but frankly, who in Europe is excited at the idea of a strong German military?

As to why Macron supported her, I can only try to speculate as to what his reasoning is:

• Not Manfred Weber, whom Macron didn't want for lack of "government experience" (official reason) and being the epitome of the CDU/CSU's views on EU government (closer to the truth); VDL has been in the German cabinet. Check.
  
• Since Timmermans was blocked by the V4 and Vestager didn't have a majority at the EUCO either, an ideal compromise candidate had to be German (check) and EPP (check) to appease the CDU/CSU still miffed at Weber's rejection.
  
• Prevent Jens Weidmann from claiming the ECB (check: this will go to Ch.Lagarde).
  
• Candidate should be a "federal Europe" type; which seems to be the case with VDL, even if her CDU/CSU colleagues are certainly not leaning that way (but Macron doesn't care about CDU/CSU feelings). Check.
  
• Able to speak several languages, including French, like Juncker or Timmermans. Check.
  
• Preferably female, to be able to brag about gender balance, "Europe is a woman" etc... Check.
  
• Still, not too strong a personality as to not rival the executive in the EUCO (starting with a young and ambitious French president). Check.

All in all, a rather cynical compromise, but that's typical Macron.