Report vs. Search
The CRM has inbuilt search functionality that covers most scenarios, so it's important to know when to use a report and when to search. Reports give users the ability to easily display complex information about their data and to display answers to questions about this information in accessible ways. It is useful when you need to repeatedly ask the same question, or a set of similar questions, about your data.
The current report interface does not support most common batch actions such as Update via Batch Profile, Smart Group creation and so on. This means that if you want to perform any action against a result set, it is better to use search rather than report.
However, in some cases, reports are more flexible than searches, and each has its own set of features. For example, reports allow you to change the columns displayed and in summary reports you can order by whichever display results you choose.