He made some good signings. He discovered Davies and Tel, Goretzka also turned out well.
On the negative side, he handed out massive contracts to the likes of Gnabry, Goretzka and Coman when it was time to renew their contracts. And now we're stuck with the two Germans as they have no intention leaving, no club will pay them anywhere near that salary.
He signed lots of flop players like Lucas Hernandez, Sadio Mané, Mazraoui, Roca, Cuisance, Omar Richards, Sabitzer, Bouna Sarr and you could also include De Ligt I suppose.
But the list of flop players is way too long for me to miss him at all. To be fair, quite a number of these players are solid names and it was hard to predict they wouldn't succeed. But at the end of the day that's on him, also to have a fetish for Nagelsmann (buying him out from his Leipzig contract made him the most expensive manager transfer in history), then sacking him after not even 2 years. That shows incompetence and very shortsight, you knew (or should've known) what you got when hiring such a young guy.
And he was only hired in the first place because of Uli Hoeness - and kept in the job for so long also. He made some exciting transfers, like those with Sadio Mané, Lucas Hernandez and De Ligt. But at the end of the day he failed in his role.
I don't miss him, that's for sure.