"Is that so?"
"Az így van?" is not really good. It is a literal translation but not used for this expression. "Tényleg?" is good. You can also say "Ne mondd/mondja!" or "Nem mondod!", somewhat close to "you don"t say".
Thank you, vvsey! I didn't realize that "is that so?" is an idiomatic expression, that is why I tried to find a literal translation. Sometimes, English seems more difficult to me than Hungarian ...
Is that so? Is that right? Really? And there are probably a few more of these. Yes, one of the hardest parts of English is the millions of idioms that you have to learn. But it is also one of the most fun parts. :)
But if you want to take this one literally, I would probably go with "Úgy van?". Or, if you want to add the demonstrative, the more natural pairing would be "ez így van" and "az úgy van".
Thanks again for the follow-up! You are a great teacher, ez tény, tény, tény! :-)