At the center of Zadie Smith's On Beauty is Howard Belsey, a middle-aged academic teaching in the humanities at Wellington College, a fictitious liberal arts college on the outskirts of Boston. The nice thing about Boston is that it's got so many well-known academic institutions already that you can give it another whole college without worrying about changing its character. Wellington's got a reputation in this universe as a den of left-leaning academics, and Howard, a British art history professor who married an African-American woman and has three mixed-race children, is everyone's dream caricature of a liberal academician. His archnemesis is Montague Kipps, a Jamaican-born black British academic who is going to be lecturing at Wellington this year. Professor Kipps is a well-known leader in reactionary political circles and a darling of the American right. He has brought his wife Carlene and one of his two children with him. That's where I'll arbitrarily stop, before I get further into the tangled connections between the many major characters.
On Beauty is at its most amusing when accurately (I imagine) satirizing liberal arts academia. It also deals well with issues of cultural identity, particularly circling around Howard's teenage son Levi. Zadie Smith has a great ear for dialogue, particularly characters who are rather less than articulate (Levi) or characters who are ridiculously full of themselves (too many to mention). I also have to applaud Smith's very, very British sense of humor in creating social awkwardness for your dignified characters.
That said, I got a strong impression that the characters, as realistic and entertaining as their dialogue can be, are really just game pieces being moved around the board. You must remember that the universe of On Beauty contains no more than two dozen or so actual people, who bounce off of each other in a slow sort of Brownian motion. Just keep that in mind, and your mind won't be blown by the coincidences that dog this story, particularly the big one in the final section, involving a painting.