These types of questions are always hard for me to answer as I end up spending too much time trying to recall stuff from Life Before Japan so that my answers are Japan specific and not just things I love and hate about life.
But that is a pain, so here are my answers of the moment.
I love feeling safe pretty much anywhere I go. I love being able to just walk over to the local combini in the middle of the night without worrying about what could be lurking in the shadows. I love being able to go anywhere and not be concerned about whether it is a "bad part of town". An extension of this is the lack of a mainstream drug culture, which is a seriously big thing for me having grown up in the thick of it...
Something I hate... Besides the heat and the frustration of Cool Biz at the moment - I hate how schools do not tell you anything until the last minute. I HATE having to run all over town to find something we need tomorrow. If you are going to need six toilet paper rolls and three empty milk cartons... Tell me more than two days ahead, please. I do not drink milk and use toilet paper at that pace.
ETA; I personally love driving in Japan. I love driving tiny little roads in the mountains, I love road trips here. Trains are great, but there are so many fascinating places that are too far from stations to be easy to get to.