GHS Fast Fret

It does what it says. You can see the difference

If you're playing only at home it may be no big deal but if you're gigging you know how strings can get "sticky" or cause to much friction which makes sliding to notes and/or chords way more difficult than you want or need be. This eliminates this issue helping your fingers to glide effortlessly saving your fingers and hands the strength needed when playing hours at a time. It's only a thin mineral oil which doesn't hurt anything if you use it correctly and prolongs your strings' sound too as it helps keep corrosion minimized.

Good product. Does help to keep strings clean which extends string life. The stuff lasts forever. I have been using it for 40 years and I'm on my 5th bottle(can?). I have 1 that is at least 15 years old. Makes it easier and quieter to slide those fingers.

I've been playing for over 40 years now (boy how time flies when you're alive) and just started using this stuff a few years back. I have found that it greatly extends string life, make strings significantly easier on the fingers and helps keep crud out of windings. It DOES NOT clean old, dirty, abused strings but it will make them easier to play. It doubles string life so with strings costing $10-$20 a set, you get pay back with the first set of strings if you do your part. Be kind to your strings.

Great.

I'd forgotten about this stuff, but remembered immediately upon smelling. The can says non-toxic but this is hard to believe. I don't understand how anyone tolerates it.

Worked good. Nothing spectacular, but did help smoothen playing.(Also made my rosewood Les Paul fingerboard look great,actually).

Plays like butter!

Been using this product for more years than I care to remember. Strings last longer, fingers fret and slide painlessly.
Each to their own, but as long as GHS keep making it, I'll be buying it!

GHS fast fret helps preserve the life of your strings, but its not as simple as wiping it on and off.
Typically when your tone suffers because of old guitar strings it is because the oils/dirt from your hands builds up on the string and even causes some corrosion. Cleaning that crud from your strings will open the strings back up because the crud was dampening the vibrations.
This product won't make your strings like new, but they can help extend the life of your strings significantly. Very handy, especially if your acoustic takes a while to settle in after string changes.
When I apply Fast fret, I through scrub the strings with the applicator, then take the chamois cloth and thoroughly clean all around the strings.