For me, personally, the biggest points for Nim are:
- "Transpiled" to C, with some options regarding runtime library, which means you can target any uController out there
- Good metaprogramming support
- Static and _strong_ typing
- Consequently, precise type aware function dispatch
- Type inference
- Good generics
Also, more stuff like covariants and contravariants and... maybe you just have a look-see? ;-)