There are some good updates requested by customers in this first subscription update:
- 4K display support
- Text enhancements
- Pumpkin spice flavored polylines (kidding)
- Performance improvements
- Some fixes for issues reported by customers and CER reporting.
There is more detailed information covered by Heidi on the AutoCAD Blog
AutoCAD 2017 Fall Update
Update: Who gets the 2017.1 Feature Update
AutoCAD and AutoCAD LT 2017 Fall Update specifically for subscription and maintenance plan customers.