10 begins with a surprise party, so the very first thing we understand about our protagonist George Webber is that he has a lot of friends. However, the party seems to make him more and more depressed the longer it goes on, so the second thing we understand about George Webber is that the good things in his life are somehow not enough for him.
The central question of this movie is: can you put yourself in George Webber's shoes? There are a lot of reasons not to empathize with him. He's gotten rich off the songs he's written. He's been showered with awards. He's got a beautiful lover. He's also self pitying and a drunk. If you are the sort of person who uses the phrase "first world problems" then this movie is going to infuriate you, because it's about a guy who got a ticket to the best shindig in town but has lost his taste for the hors d'oeuvres.
If you get beyond the superficial aspects of his life, however, his existential problems are not so far fetched. He's worried that he's inching closer to death. He's worried that his work will become irrelevant as tastes change. He's worried that the people around him are having more fun because they know something he doesn't. Being rich solves a lot of problems and removes a lot of stresses, but it doesn't make you immortal, it doesn't make you cool, and it doesn't make you capable of doing two contradictory things at once. As someone who is poor, mortal, uncool and incapable of doing two contradictory things at once I was able to see a lot of myself in his problems.
Theoretically, 10 is a comedy, but it's a comedy with a heavy heart at it's core. That tone is probably the only way that a mid life crisis movie about a guy with this much good stuff in his life could be made palatable. The movie understands that George's problems are ridiculous, so you don't spend quite as much time rolling your eyes as you would in a similar but more dramatic movie. At the same time it's good that it addresses the legitimate fears of death and obsolescence that are lurking underneath the jokes because that keeps the film from becoming too smarmy. His suffering is just legitimate enough for him to be sympathetic but just absurd enough to keep the self pitying from being insufferable.
The mid life crisis movie isn't for everyone, especially if it's about a man's mid-life crisis. His sexual fears are directly rooted in the late 1970s, when the movie was made, so there's a lot of gender politics that might seem problematic to a modern viewer. (They do lead to an unexpected pay-out, however, so viewers that stick around to the end will be rewarded.) But if you can get past the superficial trappings of this character's life and some of the dated parts of the plot to see the core of his humanity you will find something interesting, because underneath all his success George Webber is still a human being, and human beings are interesting.