The Hyperscale service tier provides the following capabilities:
Support for up to 100 terabytes of database size (and this will grow over time)
Faster large database backups which are based on file snapshots
Faster database restores (also based on file snapshots)
Higher overall performance due to higher log throughput and faster transaction commit time regardless of the data volumes
The ability to rapidly scale out. You can provision one or more read only nodes for offloading your read workload for use as hot standbys.
You can rapidly scale up your compute resources (in constant time) to accommodate heavy workloads, so you can scale compute up and down as needed just like Azure Data Warehouse
At what cost? I like Chris’s “not inexpensive” understatement here.