I use it very occasionally to get back to stage. If they're spaced from the ledge to catch most other ledge options, falcon kick can surprise them a lot with its pull back, and the initial hit is strong enough to knock them down, so it's a free get away from the ledge.
If they dodge it though, free punish. If they see it coming at all, they can just dash far back and free punish. If they shield it and are NOT that close to the ledge, WD OOS into free punish.
When you're at the ledge though, the opponent can kill you for any option getting off the ledge, just depending on what they're hunting for. When they're all over your ****, Falcon kick can be that one extra option to let you get out of a tight spot. IMO it's a one per set type deal, one per game if you're feeling confident they won't punish it for whatever reason.