Pros:
He's gotten rid of some players we needed out. He's sorted out our defense and it looks quite good, and that by playing Blind at center back which I thought would be a nightmare. He's developed a possession style which we've not had before. We are currently 2nd in the league. He kept de Gea for another season. He's turned Smalling into a world class defender.
Cons:
We are about as convincing in attack as we were under Moyes. We have too thin a squad when it comes to quality. We only seem to have one style so when it's not working we have no ideas. He shows preferential treatment to players despite lack of form. We may be knocked out of the CL in the group stages because we've been awful in Europe.
Sacking him now would be beyond stupid. But if a top quality manager is available in the summer (Pep, if he doesn't sign a new contract, or Ancelotti) would it make sense to keep van Gaal for another year? I doubt it. And let's be honest, having Giggs take over in 2017 is an enormous risk.
For his system to work he needs one or two outstanding attacking players. He's got none. Holland had Robben. His Barcelona and Bayern had top quality players. Our team may be better than what we have shown, but not that much better. We seriously lack quality. And depth.
Our lack of depth was illustrated last night when Schweinsteiger was taken off and Fellaini was thrown on. To begin with Fellaini was playing deep, which makes no sense when you don't have a first touch or any decent level of ball control, he's not even that strong in the air given his size and physicality. Then he's moved up front and Rooney is getting deep. We lost all momentum, had no ideas and didn't look like scoring.
We did have a number of chances so the margins are thin, but this team looks bereft of conviction and confidence.
Best case scenario is we actually win in Germany, which is doubtful, and improve our league form (other teams will almost surdely pick up form) and finish on a strong note, then look elsewhere in the summer. The experiment has been half successful.