Microsoft's Service Pack releases typically offer bug fixes, security enhancements and performance and productivity boosts. These collective updates are referred to as "hotfixes." The VS 2003 Service Pack 1 includes hotfixes for ASP.NET, Visual Studio .NET, Visual Studio for Devices and the four VS languages -- VB, C#, C++ and J#.
Soma Somasegar, corporate vice president of Microsoft's developer division, said this about VS 2003 SP1 here in his blog:
So how have we acted on your feedback? The first Service Pack incorporates hotfixes released since Visual Studio 2003 first shipped, Security Updates, critical fixes and other additional fixes for problems that our Visual Studio team testers have discovered. We've also incorporated bugs reported through the MSDN Product Feedback Center and the top 50% of crashes reported by the Windows Error Reporting Service. This amounts to more than 400 issues overall that we have fixed in SP1. The Product Feedback Center and Windows Error Reporting have enabled us to respond more directly to issues that you've reported.
There are 18 VB.NET fixes, which address issues such as the VB Upgrade Wizard quitting unexpectedly and VS crashing while compiling a large VB solution. Meanwhile, there are 20 C# fixes, which address problems with IntelliSense, debugging and Visual Studio performance, among others.
A complete list of hotfixes is available in this document, List of bugs that are fixed in Visual Studio NET 2003 Service Pack 1.