Complex sentence: The smaller 2.5 "form-factor hard drives generally vibrate less, are quieter, and use less power than traditional 3.5" drives, but often have lower performance and less capacity, and cost more per gigabyte.
Split into simpler sentences: The smaller 2.5 "form-factor hard drives generally vibrate less, are quieter, and use less power than the traditional 3.5" drives. On the other hand, they often have lower performance and less capacity, and cost more per gigabyte.