native code speed

extremely fast compilation times

garbage collection (although you can manage your own memory if you want)

OOP - by reference only, easy initialization, always virtual

cleaner template metaprogramming syntax, more powerful templates, as well

built-in dynamic and associative arrays, array slicing

versioning (no preprocessor madness)

link-compatibility with C

nested functions

class delegates / function pointers

module system

similar syntax

No virtual machine or interpreter

built-in unit testing and design-by-contract

My programs come together faster and have fewer bugs. Once written, the programs are easier to modify. I can do (1) and (2) without giving up performance.

DMD (Digital Mars reference compiler, Windows & Linux, x86)

GDC (GCC front-end)

For those with a C/C++ background, D offers:For those with a C#/Java background (a shorter list, but one with big wins):These two comparison sheets can go into more depth on how D stacks up against other languages.From D's creator:For me, it's hard to pinpoint any particular feature or two. It's the combination of features that makes the cake, not the sugar, flour or baking powder. So,Get your compilers and start hacking D