Pretty good but check whether you'd prefer the DS418play.
Nice NAS, great improvement on my old ReadyNAS but perhaps not as much of an improvement as I expected, given the seven years or so between products.
Software quite easy to use after a little familiarisation, but desktop quite slow.
I was disappointed to discover that it doesn't have an official Plex Media Server app - there is a beta version you can find if you hunt around. It also wasn't clear from the Synology website and the reviews I read that the DS418play would have been significantly faster, and have a greater choice of apps, for not a huge amount more.