If you are coming from C#, then you probably wouldn't enjoy checking the results of each and every function call. You know how and when to use exceptions and they will save you many lines of code over using Go.
If you have used generics then you will probably feel like you are back to .NET 1.0 when using Go. You will end up generating code for types or copying and pasting class definitions.
That said, I am all for learning a new language that will teach me a new paradigm. In that case, the loss of productivity is worth it because it will add to my toolset. If the paradigm is the same, but the productivity is lower, well then what is the point? Performance? Perhaps.
BTW, I completely agree that Nim is one very cool language. It hasn't introduced new paradigms for me (yet), but it improves my productivity over C++ when working on a small opengl game.