If you've used Juno before you may notice the much improved markdown rendering (which is of course available all throughout Juno): There's syntax highlighting, LaTeX rendering and lots of general improvements.
Apart from that the docpane UI shows most relevant information (type of the binding, defining module, whether the binding is exported etc.); a click on the binding will take you to the defining location and a click on the module will give some information on that. Links also generally work fine (external ones will open in your default browser, while those defined with Documenter.jl's
[link](@ref) syntax will start a new search).
These features will have been integrated into Juno at the beginning of September 2017, so feel free to try them!
I'd like to thank Mike Innes for all the fruitful discussions about implementation and functionality, as well as his guidance on Julia/Juno development in general (well before GSoC even started).