Short answer: he's done better than Unai Emery did with a better squad.
Longer answer:
Managed to bring back joy to the club and gave us amazing games like the one against PSG, City, and Spurs, all along laying the foundation for a rebuild by:
1. cleaning out much of dead weight
2. introducing youngsters in a tangible way
3. Improving existing players
4. Buying 3 players, all of which worked out, so far. Arguably - we bought too few, but at least whomever he bought none were flops. Which is way more than we can say about Moyes, LVG, and Mourinho before him.
In reality, his one big problem is inconsistency, but that is very much expected when you are doing a major rebuild. Other than that - he's doing a lot of positive, without creating any drama. Which takes some skill considering the mess of a situation he inherited.
We'll see if Arteta can achieve as much. I am certain, the answer is - no.
Let's get one thing straight, Arsenal did not have a better squad than us when Emery took over. I know Ole's fans like to rewrite history and pretend that we had one of the worst's squad in the premiership, but you only have to look at the overall cost of our squad to see how much more depth and quality we had across the team compared to Arsenal's team.
Bringing back the joy is an subjective and immeasurable point since many of us don't find joy in watching the team being a one trick pony and I doubt many found joy watching us getting taken to school by the likes of Crystal Palace, Bournemouth, Huddersfield, Everton and Newcastle
1. ''
Cleaning out dead weight'' - Another subjective intangible point, which simply entailed selling players(some who would have made a difference for results this season) which is the bread and butter of management. It's like praising a manager or CEO of a company for sacking members of staff
2. ''
Introducing youngsters'' - I'm sure it's not beyond Arteta to introduce youngsters, something even Emery managed to do
3. ''
Improving existing players'' - Again nothing beyond the capabilities of any manager, which is the basics of the job
4.
''Buying 3 players, all of which worked out, so far. Arguably - we bought too few, but at least whomever he bought none were flops. Which is way more than we can say about Moyes,
LVG, and Mourinho before him''.,
Mourinho bought in more than 3 players and several of them who Ole is heavily dependent on . When Ole signs 6-8 players who are outside of England and they are all successful, then you can blow his trumpet.
So going back to the main question as to what has Ole has achieved, we can conclude that he has sold and brought players, played youngsters whilst improving several existing players. All things which any manager should be doing, least of all from one of the highest paid managers in football, though I'm sure some fans are of the genuine belief that he's working for free just for the privilege of being our manager