"Jein" is definitely one of the best words in the German language. It's one word for both yes and no.
ja + nein = jein
Knowing the word "jein" in German opens up a whole new world for German learners and their eyes get really big and their ears perk the first time they hear the word. "Jein" also has several uses; for starters, "jein" allows you to give two simultaneous answers to one question.
This is perfect for difficult questions and for difficult answers.
When it's impossible to give a simple answer to a question, "jein" signals that your response can't be summed up in one sentence and that your listener needs to pay attention to your entire response.
Also, "jein" is a great response when you are still undecided yourself. "Jein," you want to move to a bigger apartment (ja, umziehen!), but your commute to work is so short now (nein, nicht umziehen!), however you'll need more space soon (ja, umziehen!), but you don't know yet how much more space you'll need (nein, nicht umziehen!).
So when you have multiple answers to a question, remember you can rely on "jein" to signal a multi-layered response.
Viel Spaß damit!