I have been playing with nim (totally private use) for a a few months. I generally use Geany as an editor. Support in Geany is somewhat mixed, and I would certainly like it much improved, but it has not been a show stopper for me.
Lack of debugger support also generally has not been a show stopper. There are times when a debugger would help, but you can generally put debug statements in the code and create small sample bits of code to try things out. Many other very popular languages also have pretty much no debugger support. What makes a language mainstream is inertia, and the size of the library support. I often revert to using Perl scripts not because Perl is a great language to use (it has often been described as a write-only language because it can be difficult to read) but because it has a large library behind it to get things done quickly. Nim does not have as large a library as languages such as Perl or Java because it does not have the size of user base to write that language (catch 22 - you need to users to write the library functions but you don't get the users because you lack the library functions). One big saving grace about about Nim is the ease with which small fragments of C code can be embedded in the Nim code to add functionality that Nim libraries do not yet have.
