There are far too many changes in SP1 to list here, but the list below is a sample of SP1 highlights to get things started. This is a list of things that you can do now that you couldn’t before, or things that are just better than they were with the original release:
•Outlook fixes an issue where “Snooze Time” would not reset between appointments.
•The default behavior for PowerPoint “Use Presenter View” option changed to display the slide show on the secondary monitor.
•Integrated community content in the Access Application Part Gallery.
•Better alignment between Project Server and SharePoint Server browser support.
•Improved backup / restore functionality for SharePoint Server
•The Word Web Application extends printing support to “Edit Mode.”
•Project Professional now synchronizes scheduled tasks with SharePoint task lists.
•Internet Explorer 9 “Native” support for Office Web Applications and SharePoint
•Office Web Applications Support for Chrome
•Inserting Charts into Excel Workbooks using Excel Web Application
•Support for searching PPSX files in Search Server
•Visio Fixes scaling issues and arrowhead rendering errors with SVG export
•Proofing Tools improve spelling suggestions in Canadian English, French, Swedish and European Portuguese.
•Outlook Web Application Attachment Preview (with Exchange Online only)
•Office client suites using “Add Remove Programs” Control Panel
Read more over here: Link