The Toshiba L15 has an SSD storage medium which is better than the HDD storage medium found on most notebook PCs that have been on the market for a comparable time to it. 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.
An SSD storage medium is in fact the best storage medium amongst all medium processor core notebook PCs that have been around for a similar time to the L15.
The worst storage medium across comparable types of notebook PC is HDD.