However, if you do a lot of collection processing, you start to really itch for something like generics (Which can lead down some pretty interesting rabbit holes: http://blog.burntsushi.net/type-parametric-functions-golang). I think this is a pretty big feature to be missing, actually. I hope it comes soon in future updates. It's pretty frustrating to have to reimplement data structures that can accomodate custom structs.
But overall, it's very impressive, and a step in the right direction. I think we're approaching a golden age of programming languages, where syntax, expressiveness, and performance are all given equal seats at the table.