I ported a smallish script I use at work (~300 lines or so) from Python to nim fairly easily since the syntax is similar. Being able to compile a small binary across several platforms is nice, though the particular library I used wouldn't compile on Windows using nim 1.0, despite supposedly working in earlier versions (the bugs appear to be in Nim's Windows support, not the library).

The biggest downsides right now as compared to Python are the overall lack of libraries, and lack of documentation (the core language is reasonably well documented, 3rd party libraries much less so).