For me the biggest problem with .NET is the fact that it doesn't generate true binaries and the deployment problems (framework needs to be installed). The advantage of Delphi is that it compiles everything into a single exe file that just works properly everywhere on any Windows machine. But if you develop in-house software or custom software for a specific customer then these reasons probably don't matter.

I have tried writing a few applications in .net and I liked it. I think it's really great for the programmer because C# language has lots of features that I really want to see in Delphi's pascal. Still, Delphi (I'm still using the old Delphi 7) is my favourite development tool.