I was born, briefly lived, and visited there several times, but only to Tokyo area and all around Okinawa.
I really like it, there's lots of fun things to do... but there's also the negative things, mostly political/societal things (I worry for women and children) tourists won't have to worry about, though.
Ive lived in Japan in the past. It was fun, and I consider it a second home. I still like it better here in the US, as no country is perfect. Most people don't realize how socially progressive the US, along with many European countries are, compared to most Asian countries (Ex: Though they claim gender equality, women as a whole are not valued as much in society, or their absolutely insane 90+% conviction rate for criminal charges, where the concept of "innocent until proven guilty" does not exist).
I lived in Hyogo Prefecture, so I would often visit Osaka and Kyoto for fun. Den Den Town was good fun to visit.
Ive also visited Tokyo on rare occasions, mostly to join in the fun of Comiket and exploring Akihabara.
Another thing people dont realize, is that Japan has a sub-tropical climate. Summers suck due to the heat + humidity. Also, winter sucks too, since most Japanese homes and apartments are not well insulated.
For sure, I want to go back and visit Japan in the future. Pro-tip: if you can speak passable Japanese, try to go to a local matsuri (not a big city one). Its a bunch of fun, especially with friends.