It's only been a week since the last Slow ring build, but today, Microsoft released Windows 10 Insider Preview build 17744 to the Slow ring. This build is also serviced from the Fast ring variant. It includes KB4459375, which has a single fix for an issue that caused a green screen of death (GSOD) when logging out of or shutting down your PC.
There have only been two Fast ring builds since the last Slow ring build, which was build 17738:
You won't see any new features, as we're very much nearing the end of Redstone 5 development. The version number is now 1809, which means that it's going to be finalized next month in September, followed by a public release in October. At this point, the team is focusing on fixes and refinements, and if you want new features, you should be on the Skip Ahead ring.
This is still only the fourth Redstone 5 build for the Slow ring. Presumably, there will be more frequent builds in the ring as we approach next month's RTM.