Is it worth learning it? What problems are best solved with it?
If you are intending to do something that has multiple concurrent tasks ongoing at the same time, I would definitely reach for Go (and maybe be very careful or skip entirely using channels). I also would reach for Go if you intend to work with a large group of other software engineers. Go is rigid; when I first started programming I thought I wanted maximum flexibility, but Go brings uniformity to a group of engineers' output in a way that makes the overall team much more productive IMO.
Basically, I think Go is the best choice for server-side or backend programming, with an even stronger case when you're working with a team.