I was living in Japan at the time the movie came out and I didn't get it at the time. My mistake was thinking the movie had anything to do with Tokyo and for me, seeing Charlotte (Scarlett Johansson) be bored in Tokyo seemed so stupid to me.
But, I watched it again 15 years later and totally got it. Maybe because I'm lost too I finally got it. It's got nothing to do with Tokyo and everything to do with 2 people feeling completely lost in their lives. Tokyo is just a setting that's different from most westerner's every day lives to try to convey that feeling of "lost" to the viewer.
Neither of them have any idea what to do any more. Their lives seem meaningless to themselves. Charlotte has been married just 2 years but she's already disillusioned in her marriage. She calls her mom very early in the movie crying because she's in Tokyo, seeing new things, knowing it should be exciting but feeling nothing. And further, her husband is seeming like a different person than the person she thought she married. Her mom doesn't listen and doesn't have time for her (same as my mom, haha).
Bob Harris (Murray) is similarly lost. He wants to find some acting project he's passionate about but instead his manager has him making commercials in Japan. His relationship with his wife is clearly not going well (listen to their conversation on the phone about a hour in) and so he's lost too realising his marriage is basically over and they're just two people who happen to be living together.
If, like the younger me, you haven't experienced that feeling of being lost, the movie will probably do nothing for you. But, If you ever get in to a point in your life where you're feeling lost, watch it again and you might enjoy it.
