How so? Everything I've read online has been roses and unicorns in terms of it's speed and build times.
Additionally, in most benchmarks, Go does fairly well and is young and constantly improving: http://www.techempower.com/benchmarks/
You will also find Nimrod / Jester in those benchmarks, and can compare the performance for yourself.
gccgo has too many issues (lags behind release, requires gcc recompile, etc.) to be useful to most people.
We have to dig through 30TB of images -- so the performance benefits we got from gccgo were worth the trivial effort it took to implement.
And then there's memory consumption...
I wouldn't say the syntax is complex because it's close to C++, but it isn't to everyone's taste (and that's fine; lots of people prefer that syntax and there's room for different languages for different folks).
More likely, probably people hate those two points so much that they forget to mention other problems. Which is a pity. Please tell us about other problems.
However, let's be clear that the pointer semantics do bring a great deal of complexity to the language.
That said, I'm very impressed that the managed pointer sigil has been eliminated and the feature moved to the stdlib. That and the fact that Rust's team has clearly pushed the message that owned pointers are the idiomatic way to deal with memory in Rust have combined to bring a lot of clarity to the language. Also, as stated above, I really like the direction that the standard library is taking. So congrats on a job well-done.
Edit: Let me also congratulate you on the Rust compiler error messages, which are almost invariably clear and actionable compared with other languages I'm playing with in this space.
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.