Any changes you need to make, adding more capital, change address, requires again, paperwork, tons of hours and again the notary.
Taxes are also quite difficult to figure out, I'm not German born, and my German is good for conversation, but to read and understand the tax has been a problem and I had to rely on very expensive tax consultants. (I know, this is my problem, not a german problem)
It's not that is hard, it's very time consuming, manual, and involves a lot of paperwork. Other countries do this much easier. Also, shutting down a company... I'm still trying to figure that out :(