The ThinkPad X1 Carbon has an SSD storage medium which is better than most medium processor core laptops that have been around for more than a year. Most medium processor core laptops that were released one year ago 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 amongst all medium processor core laptops that are a similar age to the ThinkPad X1 Carbon.
The worst storage medium amongst similar types of notebook PC is HDD.