The Surface Pro 3 has an SSD storage medium which is better than most laptops of this age and spec. Most portable PCs that were released more than two years 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 laptop's storage medium (SSD) is actually the best storage medium amongst all comparable spec notebook PCs that have been on the market for around the same time as the Surface Pro 3.
Amongst similar types of laptop the worst storage medium is HDD.