He has been okay, but not great. I would say:
Maguire - decent player but probably overpriced for 40m. At best, marginally better than Lindelof, so should be second/third choice.
AWB - no business being at United.
James - had no business being here
Bruno - great signing.
VDB - why did he sign him in the first place?
Diallo and Pellestri - what was the point on signing them and never playing them, especially with other talented kids coming from the academy.
Cavani - very good signing.
Telles - possibly ok backup.
Varane - should be a great signing, although I don’t think there would have been a single manager who needed a CB, and had the opportunity to sign him who would not have done so.
Sancho - what was the point on signing a system player if you don’t have a system in the first place. We also have Rashford and Greenwood who are better than him, in addition to Martial, Lingard, Diallo, Pellestri and Mata who play in the same positions as him. All players signed, promoted or given a contract by Ole.
Ronaldo - should be a great signing if you manage to feed him.
So in general, I think that except Bruno and Varane (I think Varane would be great under any manager), all others have questions marked. A bunch of player he has no intention to play (VDB, Diallo, Pellestri), system players who he has no idea how to use (VDB, Sancho, Ronaldo), ok player but get Beckenbauer treatment and cost the moon (Maguire), okay backups (Cavani, Telles), and bad signings (AWB, James). It is probably not terrible like Van Gaal’s signings were, but nothing special too.
He also was not happy to sell players we didn’t need. Henderson should have been sold cause he could have fetched good money, while clearly not being good enough for us. No one can explain why Jones, Bailly and Mata got new contracts, and no one knows why Lingard got offered a new one. All players that should have binned with immediate effect when we had the chance.