1. school fees (more expensive)
2. can not socialize well (no experience of interaction / social competition)
3. Curriculum materials can be adjusted to the child's ability level
Well... I object to the school expense one because, technically, public schools are free... so the expenses should not be significantly different from that of home school. I would actually think that home school is more expensive because you will have to purchase or rent textbooks and materials through local schools.
Another topic I might add is how there is limited materials/classes available at school while at home, you can even learn classes and materials that are not offered at school. At my school, for instance, the only AP's offered are: Chem, Physics, Calculus, English Literature, Biology, and Psychology. Others, we have to learn on our own.
And, by the way, please make your subject more specific and helpful. Right now, your thread is in danger of being deleted by the moderators. Just a heads up :]