That’s a change from previous updates, which often targeted the Creators Update exclusively. In general, it improves performance, reliability, and battery life.
Surface Pro 4 Firmware Changelog
However, if you want to get into specifics, Microsoft has now made the full changelog available:
Microsoft Driver update for Surface Embedded Controller Firmware: Surface Embedded Controller Firmware 103.1684.256.0 improves battery life during sleep. Intel Corporation driver update for Intel Precise Touch Device: Intel Precise Touch Device 1.2.0.83 disables touch when cover is closed, and improves stability. Surface driver update for Surface Integration: Surface Integration 1.0.121.0 adjusts system Hibernation defaults. Microsoft driver update for Surface Touch Servicing ML: Surface Touch Servicing ML 1.0.724.0 optimizes touch functionality. Surface driver update for Surface System Aggregator: Surface System Aggregator 103.1610.256.0 resolves screen brightness issue when device comes out of sleep. Surface driver update for Surface UEFI: Surface UEFI 106.1624.768.0 refines brightness settings. Microsoft Driver update for Surface Touch: Surface Touch 57.1.1.1 optimizes touch functionality.
This is the most significant update in a while, and it’s good to see Microsoft’s continued support and improvement. Though there’s nothing about it in the notes, there has been speculation about Surface Dial support and the new Pen. It’s hard to say what’s included in “optimizes touch functionality”, but I wouldn’t get your hopes up just yet. As usual, you can get this update by heading to Settings>Windows Update>Update Now. They come on a gradual basis, so if you don’t see it yet then it may be in your region later. You can read the full changelog here.