I have a GSD. He's two now, and the most loving, loyal and protective dog I've ever had. But it took a lot of work to get him to this point.
I don't regret him for a second. He was the best decision I made, although I admit there were times through the raptor stage I wondered what I had done.
If you do it the hair is unreal. They only shed twice a year. For six months at a time. You'll never go to the toilet alone again. They are a very vocal breed and I don't mean barking (although they will do that) but I will have flown blown conversations with him 😂. Some of the grunts and groans he makes are hilarious.
They are intelligent too, he has worked out how to open all doors, knows what certain shoes mean, and I swear he can spell. He likes his own space and the freedom to take himself off when he wants so I recommend somewhere for that. The rule being if he's there, no one approaches him.
Do I think you're mad? Not in the slightest, but don't do it lightly and do your research. They take a lot of work and a lot of time and effort. You get out what you put in though. They are very very bitey as puppies and will push boundaries. You have to be hard with teaching them what is acceptable and what isn't.
I will say research the differences between working and show line. Mine is working line, which means he is straight backed and less likely to be susceptible to hip and elbow displacement (although we're having him scored in the next few weeks). However, the trade off for that is he is high energy and has has a high working drive all the time.