I like to see my kids have math homework. That way I can see if they aren't grasping a particular concept, and give them more help with it. Waiting until a parent teacher conference to hear "your kid doesn't XYZ math concept" weeks or months later seems troublesome to me. Plus, with math, different kids take differing amounts of time to get a particular concept. For my older child, it ended up that I ended up practically homeschooling her in math for a couple of years, because there was very little homework and the curriculum was low quality.
I'm not as concerned about homework in other subject areas.
I think Kohn has some good points about homework. Some of what he says The Homework Myth troubles me, though, and seems contradictory. He says in a couple places in the book that some groups will be more likely to do homework, and others will not...thus widening the achievement gap. Then he basically states that is a reason NOT to give homework. I found that troublesome. If you have the book I think these passages around page 127, and 187.