The concept of the Seagate Central is a good one. The hard disk behemoth wanted to develop a user-friendly NAS device, and to keep things manageable for less experienced end-users it kept features to a minimum. If all you want is to share files and be able to access them online and via mobile apps, then you don't need the vast range of features from a QNAP or Synology NAS device.
Slow computer got you down? Maybe a hardware upgrade should be in your cards, if so this guide to the Fundamentals of Upgrading a PC is an invaluable read. PCSTATS Tips