The Bite-Sized series of articles is meant to take the most powerful cards in Dominion and give a short explanation of what makes them powerful.
The power of Island Folk, like any other Ally, varies a lot depending on which Liaison(s) are in play. However, the ability to take extra turns makes any Liaison worth focusing your strategy around.
When Island Folk is around, you usually want to just get as many Favors as you can so that you can take two turns at a time. Just be careful with some Liaisons, though. If you’re consistently getting your extra turn, you don’t need to make 5 Favors per turn to keep that up, since you’re likely to be playing your Liaisons twice before you need another 5 Favors.