the main advantage of the koma classes are that they are much more flexible than the standard classes. Especially in recent releases, it is very easy to adjust almost everything you need with a nifty command, and it features some very useful document class options and extra environments.
Most important, it is very well documented. scrguien.pdf, the manual, has >200 pages currently.
do not forget that a lot of the options are especially for the europeans. The memoir class might be an excellent alternative, but someone has to write a layout file ...
Herbert
