Osaka is beautiful, the Japanese student that we hosted told about it and I googled a bit. About the castle... wow hopefully you knew before hand about the CGI that they used in the Series, I would be very disappointed to expect that castle and find something different. To be frank, in many experiences when travelling I faced disappointments...high expectations and checking what really is! ( I don't remember right now but this feeling isn't new).
I knew about it. Wasn't exactly planning to be there, but had some time in my hand and felt why not.