Aside from improving the points total, goals scored, goals conceded and winning a trophy, I think there are a few more things to cause a positive review of ETH's first season as a United manager.
1. We are far better when it comes to getting more players into attacking positions without (mostly) compromising our defensive balance. When we attack, there are more players in and around the penalty area than there were with Ole or Mourinho (or Rangnick, though he may not be relevant). It has also lead to some more threat against organized defenses, though there is still a way to go there.
2. When playing out from defense, there seems to be more of a plan. We used to see quite frequently how our fullbacks received the ball under pressure from two or more opposition players. Wan Bissaka struggled with this and it is why his passing ability has become underrated. I'm not saying that he is a good passer, just that he is not as bad as has been perceived. Shaw is far better in those positions but he still found himself frequently in situations where he had no good passing lanes except back to Maguire. And we all know Maguire is not the player we would want to have the ball under pressure.
I think ETH underestimated the problems with mentality in the squad when he took over. He alluded to this after the Brentford game, saying that the team "lacked faith". That defeatist mentality is still there to some extent - we have seen it against Liverpool, Sevilla and to some extent, Newcastle away. Whether he can remedy that remains to be seen but winning games and trophies probably goes a long way.
There are some other things which could also be pointed out but this is long enough.