I'm not a big fan of De Gea. I think that Fergie would have signed someone like Begovic or even Valdes if he was still there now.
Even with the new signings, I don't think they really have any defenders who enjoy defending. Rojo looks like a cross between a left-sided centreback (in a three) and a leftback. Presumably they tried to tempt Dortmund into swapping Hummels for Kagawa. He would have been perfect for them. As a stop-gap I thought that LVG might have tried to take Vlaar from Villa to give leadership to Jones and Smalling.
They don't have any defensive midfielders either. Fellaini can't cover the ground and gives away too many soft fouls, Blind is more of a utility player and Herrera is a box to box midfielder.
If they want to play two up top and Di Maria then surely Mata will have to move out wide or be sacrificed. It seems like they've bought as many big names as they could and that they'll think about how to play them later. It doesn't look like the blend is right to me though. Van Persie was already complaining about players taking up the spaces that he wants to play in and he could find it even more difficult if he's joined up front by Falcao.
I agree with Phelan that United shouldn't be jettisoning English players like Welbeck and Cleverley. They're still very young and they're good enough to be squad men at least.