Advantages of Visual Studio 2008 over Visual C++ 6.0:
Much more standards compliant C++ compiler, with better template handling
Support for x64 / mobile / XBOX targets
Improved STL implementation
Support for C++0x TR1 (smart pointers, regular expressions, etc)
Secure C runtime library
Improved code navigation
Improved debugger; possibility to run remote debug sessions
Better compiler optimizations
Many bug fixes
Faster builds on multi-core/multi-CPU systems
Improved IDE user interface, with many nice features
Improved macro support in the IDE; DTE allows access to more IDE methods and variables
Updated MFC library (in VS2008 Service Pack 1)
support for OPENMP (easy multithreading)(only in VS2008 pro.)
Disadvantages of moving to Visual Studio 2008:
The IDE is a lot slower than VS6
Intellisense still has performance issues (replacing it with VisualAssistX can help)
Side-by-side assemblies make app deployment much more problematic
The local (offline) MSDN library is extremely slow
As mentioned here, there's no profiler in the Professional version
In the spirit of Joel's recent blog post, I've combined some of the other answers posted into a single answer (and made this a community-owned post, so I won't gain rep from it). I hope you don't mind. Many thanks to Laur, NeARAZ, 17 of 26, me.yahoo.com, and everyone else who answered. -- ChrisN
