Gel baits, any feedback

I like the sound of these but has anybody actually fished and caught with them on here.

As i say i like the sound of them, but are they just a bait gimmick or seriously work.

I saw them in a tackle shop over here in France and was nearly tempted,but will wait and see if anyone catches on them first.They looked good and must absolutely leak smell and on the jar they claim they would last days.