I've recently started one
Advantages:
* Any capital gains, growth, dividends, etc. from the fund are all tax free as long as the money is withdrawn for qualified educational purposes.
* In a lot states have plans that allow you to write off your initial contributions from your state income tax earnings. Granted, this isn't near the benefit of writing it off your federal return like 401k contribution, mortgage interest, etc. But it still helps.
Disadvantages:
* Most 529 plans are pretty strict about what you can invest in. They won't let you get too risky, which can be both good and bad.
Overall, I went with the Arkansas plan since I'm an Arkansas resident. It gives me the state tax writeoff. I've been pretty happy with it so far. Really, really smart to set up monthly contributions when they're real young and have a nice little college fund when the time comes.
BFB
Has anyone opened one of these saving for kids education? Advantages, disadvantages?