The HP Ultrabook 13 has an SSD storage medium which is better than most notebook PCs that have been available for a comparable time to it. Most comparable spec notebook PCs that came out around the same time as it have an HDD storage medium. Solid State Drives (SSD) store data in semiconductors on a circuit board rather than using magnetic or optical media. Solid State Drives have no moving parts which makes them very fast and reliable.
This notebook PC's storage medium (SSD) is actually the best storage medium across all medium processor core notebook PCs that came out around the same time as the Ultrabook 13.
Across comparable types of notebook PC the worst storage medium is HDD.