The transmission can be an big issue.
I got really lucky, that my transmission issue was fixed at BMW goodwill after the warranty expired.

It was a control module that went bad. The fix would have a cost of 3700 including parts and labor, but glad they got it fixed for free (one year after warranty expired).

They are not fun to deal with. I would have hoped more from BMW in reliability department, especially considering how much these cars are sold for, and what BMW stands for.

Oh well
Live and learn

On the other hand, the electronics and transmission issues are very common for BMW.