Any IDE that wants to challenge VS has an uphill battle in what concerns:<p>- GUI editors<p>- Parallel code debugging<p>- GPU debugging<p>- Enterprise code navigation<p>- Edit-and-continue<p>- Debugging native code generated for .NET applications<p>- Mixed language debugging<p>- GUI Profiler<p>- Code Profiler<p>Just a few items on the top of my head.