Kohn (as usual) spends so much time reviewing the eductional literature, you wonder how he stays sane. Educational research is not, after all, particularly well-executed at its best, and he demonstrates clearly how often the conclusions and policy directives diverge sharply from what little evidence there is.
The set up is simple. Homework does not help and probably does harm in younger children. More homework is not better. Practicing stuff wrong is really pointless and disrupting the limited amount of time families have to spend together is an undesirable effect even if it did improve academic performance, which it does not.
Kohn is sane enough to realize that individuals -- whether parents, educators or administrators -- can't change things unilaterally. Some parents demand a heavy homework load. A lot of educators and administrators believe it is necessary. He does have a number of suggestions for mitigating harm, and pulls out all the stops in identifying which aspects of the current advice/practice can be used to move things in a better direction (e.g. using the 10 minues/grade level as a maximum, not having homework every day, offering time in class to do the work so feedback is available, assigning pleasure reading and trusting the kids to do it without putting time or page requirements or requiring book reports).
A lot of what he talks about ties in well with his earlier work on intrinsic/extrinsic motivation. He also pulls in social justics issues and identifies how political rhetoric tends to drive homework policy.
Good stuff. I suppose if you don't have kids now and never expect to, you wouldn't necessarily need to read this, but even if your kids are grown, there is, presumably, a future generation.