At best it's a nightmare. On a bad day, if there's been an accident, you might want to murder someone. Probably not yourself, though maybe. It's no accident that road rage was invented here in LA.
Unfortunately, I live in the Valley and work in Santa Monica, which means that I, like an awful lot of people, have to cross the busiest stretch of road in the world - the intersection of the 101 and the 405. Looking for alternative routes has been something like a hobby, and something more akin to a Grail Quest. The best way into work I've found has my climbing up through the hills and over Mulholland Drive to creep into the city through the surface streets. There are still some bad parts, and all told the time saved is pretty minimal.
But oh, have I found the best route to go home! I can go the few blocks through Santa Monica right up to the beach, and drive up the Pacific Coast Highway - right alongside the ocean - into the Topanga Canyon. Then I take the Canyon all the way through to the valley, winding up, down, around, and through the mountains in a glorious, twisty, fun and really scenic route. I love getting to see the sea every day on my way home. Every day its color and texture are different, every day the sea has a different character.
Unfortunately, the reverse trip is not practical because the light that goes from canyon to the PCH is very slow, and traffic stacks up for miles. But on the way home it moves steadily, and is at least 15-20 minutes faster than just slogging through traffic on the 405 ... not to mention infinitely more scenic and relaxing. Come summer, there are beaches on the way home which I expect I'll stop off and visit.