Google Analytics Search Engines Report is quite a simple report that shows you which search engines visitors are using to find your site. It also shows you the relative quality of these visitors, segmented by their search engine, in terms of the usual metrics: Visits, Pages/Visits, Avg. Time on Site, % New Visits and Bounce Rate.
So in the above example you can see that Google was by far the most popular in terms of generating visits, and also provided decent depth ratings with pages/visit and avg. time on site revealing quite respectable stats.
This information is quite useful when planning a Search Engine Marketing campaign because you can use it to tell you which search engines are likely to yield the greatest Return-On-Investment. If you see that one search engine is providing you with good quality visits, you might like to consider a Pay-Per-Click SEM campaign to generate more visits from that search engine.
The search engine report can prove valuable for the evaluation of search engine optimisation efforts. An increase in visitors from a particular search engine indicates that your website is performing better in that search engine. Considering Google is constantly changing its secret ranking algorithm, this report is critical to evaluating whether your search engine optimisation efforts are having any impact on your website's rankings.
Drilling into the report further (by clicking on one of the search engines listed) brings you to a report showing you the keywords visitors used to find your site, again with the usual metrics. This is excellent information for determining what keywords you could, should or shouldn't use on your SEM campaigns for particular search engines. It may also highlight Search Engine Optimisation and Marketing issues if many irrelevant terms are pointing to your website.