Ben,
Information is information. Semantic content more or less is a buzz term / jargon for something that should already be taking place on any well formed web page.
Using color to highlight the information that you feel is important, meaning the information that you want the user to act upon obviously when done correctly yields the warranted results, likewise when done improperly yields negative results.
The immediate benefits when applied correctly can range from readers responding with impulse, to easier comprehension and digestion of the information (semantic content) resulting in the desired action or implied call to action.
Drawbacks essentially yield negative results, so there really is no need to explain them all. It's, whatever it is, that you don't want. On the otherhand a drawback that may be of no consequence is a compromise in design or visual appeal, which only matters to the asthetic focused, but like I said if you users are responding as you wish that really can't be seen as a negative.
Analyzing should be based around action, implied actions, benefits, calls to action, impulse, topic sensitivity. However color is nothing without proper placement. Great colors go nowhere without a great design.
A perfect example of a website using minimal color and getting the job done is
Apple The whole site is almost black and white and has been for the last few redesigns. It is constantly one of the most respected designs in the world.
