Automatic Update of the Database via Excel

I have this requirement where the user downloads a huge Excel report from CRM On Demand. Then he modifies the spreadsheet. Now he wants to know if it is possible to import the same report so that the changes would be captured automatically by the system. Is this possible? Or is it just a matter of downloading the report, saving the edited report as .csv and then do the data import? Is this advisable? Is anyone doing this regularly? If yes, is there any safer, faster and less manual intervention to do this?

I would appreciate any advice that you may have. I am however particularly interested on anyone that this actually doing this and not ending up with messed up databases.