Our business in general has been pretty good in difficult circumstances, not that you'd know it from here of course. Getting £50m for Welbeck, Hernandez, Evans, Buttner, M.Keane, Bebe & Kagawa was impressive. Likewise finding buyers at all given the wages and various problems with RVP, Anderson, Fletcher, Nani & Rafael.
In terms of transfers in I don't think anyone can really complain at the costs associated with Blind, Romero, Shaw, Herrera, Rojo, Schweinsteiger, Schneiderlin, Depay & Darmian. They are all either meeting or outperforming expectations, given the roles they were bought to fulfill. The only real problems have been players coming in with a huge reputation and not meeting expectations - Falcao/Di Maria cost us somewhere in the region of £25m plus wages. Again it would be difficult to argue the club could have foreseen these players failing miserably.
The final sticking point is seemingly the cost of Martial, which is exceptionally high. However it can't really be judged as a success or failure for 12-24 months. Given how some of the fans on here were celebrating like we'd won a trophy upon signing Di Maria/Falcao and how that turned out; it would be quite ironic if Martial matched or even surpassed the expectations associated with his fee, after many fans seem to be lambasting his signing.
I'd say Van Gaal has undergone one of the most successfully quick re-building jobs that could be expected since July 2013. It's other elements of Van Gaal's management that should be under scrutiny; certainly not his transfer policy. Especially as this re-building job has given us the wage freedom to aggressively go after the likes of Pogba, Bale, Reus, Greizmann etc and any other potentially World Class players as and when they become available.