[IshKebab]

I think async/sync is a big example as someone else mentioned.

I'd also say the macro systems. Macro by example is a totally new (and let's be honest, awful) language, and the proc macros are another thing again.

Thankfully I find I very very rarely need to actually write macros, and you can avoid async most of the time unless you're doing web dev.

Still a fantastic language - easily the best at the moment IMO, but I see his point.