There seems to be alot of "black and white" opinions going, that it's either 100% good or 100% bad. I think there is a middle ground when it comes to Ole. He did good and he did bad, but in a top club where you want to be among the best you need someone who does alot more good than bad. Ole didn't, and he never had the skills to do so.
Oles team came 3rd then 2nd, and isolated those finishing positions are good. It doesn't mean everything was getting better. Considering how a league position also relies on the performance of the other teams in the league one can't judge on-pitch improvement purely on the league positioning. Mourinho finished 6th in 16/17th but with 3 points more than Solskjaer did with his 3rd place. He drew 3 matches Solskjaer lost, but due to the performance of other teams people judge Solskjaers more successful?
Ole was the first manager post SAF to finish two consecutive seasons in top 4. He was also the first manager since Moyes to not improve on the performances of the previous manager. That doesn't automatically make him the worst post SAF, it just means Mourinho raised the bar to a level Solskjaer couldn't manage. Looking purely at the results of every game during the season, ignoring trophies or league positions, Mourinho won the most and lost the least. Solskjaers two full seasons were both better than LvG and Moyes seasons looking at points pr game and win rate, but they were well behind Mourinho. Solskjaers best season had a total win-rate of 57,38% while Mourinho reached 66,07% in his 2nd season. Even Mourinhos first season had a win-rate of 57,81%.
Ole was also the first manager post SAF to have a worse goal difference in his 2nd full season compared to his 1st. His defensive record in his 2nd season is the worst any manager had in a full season (Moyes included) post SAF, and by a good margin. This doesn't fit the "things were going the right way" so I rarely, if ever, see it mentioned. When you spend 150m+ on defensive signings that is not the way it should go if you do it right. Of course he also delivered the most goals offensively post SAF, but for every goal he increased offensively it cost almost 2 defensively. So the bad far outweighted the good.
This season Ole was the first manager post SAF to record a negative goal difference for the games he managed during a season. Also being the first to loose as many as he won.
Looking at Rangnick I find it funny how many of the same who defended Ole and said "time, he needs time" are on Ralfs back quickly due to things not working out immediately. Granted, the results have been poor, the win rate is as bad as Mourinhos last half season. But its improved from what was served from Solskjaer this year. The win rate is as good as equal but where Solskjaer lost a staggering 41,18% of the games, Rangnick "only" looses 25%. Offensively the avg goals pr game is equal, while defence has gone from shipping 1,71(!) pr game to 1,50. Still a high number, way to high for a Man Utd team. Rangnick has been dealt a poor hand and he haven't been able to improve it on the pitch. Hopefully the hornets nest hes shaken about off the pitch will improve the club for the future.
I think the legacy of Solskjaer will be that he did a ok job as a interim. Came in and turned the mood after Mourinhos toxicity, but should never have been given the job on a permanent basis. (His point pr game in the interim season was lower than both of LvGs seasons, just marginally better than Moyes)
He came in and promised a whole lot of changes, but could only deliver on a few of those, leaving behind a toxic unfit/lazy squad that needs a total and fundamental rebuild.