The majority of the arguments are just FUD. They might have applied in 2001, but to write this post now is just silly. He complains about breaking changes between 1.1 and 2.0 -- 2.0 came out in 2005. My guess is that he's really just angry because Microsoft (and most developers) have moved on from Delphi.
Some of the arguments are reasonable when applied to desktop development, but they're still pretty light on facts. None of them are particularly reasonable when applied to web development.
He laments that GDI+ isn't hardware-accelerated, but if I recall correctly, WPF (the newer UI toolkit that came out in 2007) is.
"Almost every programmer said you have to write XAML by hand" -- I won't defend Microsoft's obsession with visual tools, but I learned that I have to write HTML by hand years ago, and I'm not complaining.
String processing is slower? Probably because .NET strings are immutable, which actually creates large performance gains in the vast majority of cases.
If your performance concerns are so stringent that you need to worry about whether the type system in a language is rooted, you're either over-optimizing or you should be working with C.
I rather think that he's looking from another perspective. Using Delphi, speaking about speed, complex GUIs which need a visual designer (etc.) means that he is a desktop developer.
