Specs are quantitative aspects of the option such as the price
Pros
Pro
Very customizable
RetroArch is built to be an extremely customizable emulator. You can edit and customize almost every part of the emulation experience (shaders, overlays, frame rate caps, controls, etc.)
The sheer number of options and settings that it presents the user with make it extremely hard to set up for beginners. It's not for the average user, it's for people who want to tweak their experience with emulators to the tiniest detail.