With my Ford, I was curious about the condition of the engine after 300k miles. Are bearings worn? Is there a coolant leak? Is my oil protecting the engine? Sure you can do a compression test, but that only tell you so much. I could have used my borescope camera, but again, you only get so much info. With this oil analysis, you can learn a lot about the condition of your engine.
Source: http://www.fullsizechevy.com/,google