Hello!
It's great that you've taken the time to do research and think about it before hand, alas so many people don't.
German Shepherds are a great breed, however I would say that as with many herding breeds they need more exercise and mental stimulation than a non-herding breed. So daily romps at a park might not be sufficient, these dogs need to have purpose in their lives, so you would do well to get involved in some type of pursuit suitable to the breed.
As you will know from your research the GSD is also a guarding breed, and unless you specifically want this trait, then if you get a puppy you need to behave in such a way right from day one so as to prevent nurturing this instinct inadvertently.
You might find the following helpful:
Hope this helps