* Overall it's a very affordable place and people are friendly by default.
* It is a free world Country if you care about freedom
* People take privacy seriously as parts of their daily matters, minimal data share. (unsure about the lucrative advertising business, please enligh)
* Comfortable level of tech, you can say it's low tech, but they got all the details right, and experience is great. (No aggresive behavior analysis, rare ily seen QR code for menu/ordering)
And some realities to offset the love: (Ordered low to high on impact, by personal feelings)
* Unfair compensations, a large majority of companies pays their employees in a Nenko System, basically your salary increments by the x years of service inside the company
* HIGH welfare tax, Nenkin will take away around 10% of your PRETAX income.
* Language, I love this Country and I would like to learn their culture and their language
* Etiquette, the Japanese way of daily routinal interactions are very much formulated, you can take vantage of that when you are fresh off boat and trying to do basic things like shopping and lodging. But say if your goal is to integrate into their society, it's going to be a long painful journey for the talented. I got a few friends spent better half of their lives in Japan who just gave up on becoming Japanese. One of which quitted so well that he occasionally violates social norms.
Bottom line: you will need a strong incentive to stay in Japan and start/move your family here, and your first experiences won't be good. So why would foreigners stay if it's next to impossible to become local. If you are doing well enough in the Country you are already within, then you definitely would miss it and go back.
* People are friendly by default
This can be a common mistake made by tourists (or short time visitors). There is a difference between polite for money, cultural fake politeness, and actually more friendly and welcoming than average. Hotel staff can be very polite (as trained to be for money), but that doesn't mean random people on the street, clubs, housing agents, or business owners actually like every or any foreigners. And the extent of politeness or friendliness shown can depend on skin color, known country of origin, or language spoken.
* Very affordable place
This is quite laughable. It depends on your salary and where you are from, but clearly there are cheaper countries in the world than Japan. If you are rich or nearly so, many countries are "affordable".
* Non-free Country versus free world Country
Freedom is relative. For instance, in Japan, police can arrest, question/interrogate (some have claimed torture) you, and hold you for weeks without a lawyer (nor allow you to call one). Compared to other countries, this is quite draconian and backwards. Where for others, that there is any process where you aren't killed at whim or have no to little means to seek true justice, means greater "freedom".
* Comfortable level of tech
While this is quite true, Japan is not the only country that possesses significant technology. The level of street cleanliness, sewer system (like open sewers), garbage collection (dropped on street or in cans), design and width of city streets, safe train systems (protecting passengers from falling/jumping onto tracks), etc... These points all add up and how "comfortable", can be a matter of where you are from and what you were used to.