Since it was the first time cleaning the bottom bracket, I was a little nervous. Well, the biggest problem so far was opening the lock-ring holding it in place. I have a tool for that, but it proofed to be just a little bit too small. I tried to hammer it unlocked, but with no success. So I went to the nearest LBS and borrowed one special key. The guy here is very helpful and I thank him for this.
Inside the frame there was of course some dirt and it had a very rusty colour. However, I was pleasantly surprised that the inside of the frame is painted as well, so not much rust here.