I've played with the new GDC version today. Overall it seems solid, but I've encountered some issues that are probably Phobos-related. Since this is my first 64-bit D compiler, I wonder whether some parts of Phobos might not yet be 64-bit ready.
I'm pretty sure there are certain corner cases. This is a tiny one: http://d.puremagic.com/issues/show_bug.cgi?id=4310
