Before i bought the GHS Fastfret, i used the Dunlop Ultraglide 65 to clean my strings. Dunlop's cleaner was cumbersome to use, left a weird feeling on the string and fingers and the effects were very short-term, plus it made the strings TOO bright and i play with clean, zingy tones so that means something.
The GHS Fastfret is completely opposite. It's super easy to use. No dabbing, shaking and waiting for the applicator to saturate with the substance in the bottle.
Smells faintly of almonds and you can moisten your fretboard with it, since it's based on mineral oil. The effect is longer term, doesn't feel greasy or weird on the strings and fingers and the strings don't get too bright and metallicy with it. Plus, the cloth that comes with it is very smooth and doesn't leave material between the windings or around the bridge/nut if nicked.