After my last visits (and review) from 2 years ago, I'm happy to report that they have made *huge* strides in re-opening many of the departments. And did a great job to boot!
Some favourites are still under construction - physics, mines, ships among them - but a large number of the others are all open and modernised. Aviation especially has seen a wonderful overhaul!
Possibly because of some areas still under closure, you may find yourself backtracking, rather than following a circuit, but it's not a big deal.
One thing I did *not* care for: the new restaurant. Yes, the old one had all the charm of a corporate canteen (and you would see employees eating there), but it offered good Bavarian fair. Now they went more of a "gastropub" style with, when I visited, a very limited menu.