Insight: Great at providing insights into how consumers interact with your web efforts. SiteCatalyst gives a level of detail which is missing from something like Google Analytics. While GA provides great summary metrics, SiteCatalyst provides drill-down data which gives significantly more insight. For example, while Google Analytics can tell you when someone last made a purchase, SiteCatalyst can show you which path that person took to get to the point of purchase.
The product is very powerful, but not difficult to understand and use. I taught myself how to use it from the manual without too much difficulty.