The language is actually pretty amazing — it's expressive and flexible (eg., type inference lets you omit types in most places, to the point that much of your code ends up looking something like Python/Ruby/Lua), and it's just amazingly fast, but not at the expense of ease of use. In almost every way, Nimrod is the "speed of C/C++, ease of Ruby" replacement that we have been looking for. Go's performance has been too disappointing, while Rust is a wee bit too complex. Nimrod feels just right.
As I wrote in a different thread, I and a colleague have been looking a little bit at using Nimrod as a game-logic language, as a replacement for Lua. Lua is pretty fast, but Nimrod is considerably faster; I'm personally also not a fan of Lua with its very weak table-based OO and rather idiosynchratic syntax, although I know it gets a lot of love on HN.
What makes Nimrod particularly suited to game development is that it's designed to integrate well with C. Nimrod compiles to C, and the generated C code provides the necessary bindings so that you can easily call Nimrod functions from C without an intermediate translation layer. In other words: If you write your core engine in C, scripting the game with Nimrod is (from what I can tell) as easy as with Lua. Very exciting.