What's so good about hi-res audio? The main claimed benefit of high-resolution audio files is superior sound quality over compressed audio formats such as MP3 and AAC.

Is hi-res audio a gimmick?

Yes, by itself it's a gimmick on anything. However, hi-res audio may or may not use different mastering techniques than the regular consumer version, so that can lead to hi-res versions having better sound. Mastering affects the sound far more than hi-res does.

What is the meaning of high res audio?

High-resolution audio (High-definition audio or HD audio) is a term for audio files with greater than 44.1 kHz sample rate or higher than 16-bit audio bit depth. It commonly refers to 96 or 192 kHz sample rates.