Quite like the access reports but with greater functionality.
Basically, when you produce a new report, it prompts for your db connection. You can connect multiple databases from here. I have have connected an access db to an SQL db and an Oracle db in a single report.
You then have your design view which will have your field Explorer box listing all fields from selected tables.
Features include,
Database Expert (Creating the relationships between tables,fields)
Select Expert (ie, [Status] does not equal "Closed") quite like conditional formatting in access/excel
Section Expert (Customises section)
Formula Fields (you're own made fields within the report)
Parameter Fields (ie, From, To)
Top N Sort (ie, Show only top 10)
I quite like Crystal. We have also invested in Crystal Reports Distributor which sits on a server and pumps out timed reports automatically. Good tool.
Hope this helps get you started. Let me know if you have any specific questions or queries.