If you check the version listed below you will notice that the client had a few adjustments between these 2 versions including language localization, multitasking, bug fixing, OS support, contact listing mode, etc. You can also check the Wikipedia entry for Skype.
5.2.0.1523 - 5 July 2011
- Improved Multi-tasking
- Group Screen Sharing
- Sidebar enhancement
- Support for Mac's built-in HD and Logitech's B910 HD cameras
- Minor bug fixes
5.2.0.1572 - 26 July 2011
- Updated localizations
- The removal of "Professional Account"
- Minor improvements
5.3.0.1074 -8 August 2011
- Updated contact list view
- New contact grid view
- Support for OS X Lion
- Minor improvements
5.3.0.1093 - 1 September 2011
- Sometimes Skype crashed during video calls
- Fixes a problem in Norwegian localization, which could lead to client freeze
Yes, you should update in order to fix some minor bugs and have the best functionality for the program.
