There are 3 flavors: Three Cheese, Kickin' Ketchup, and BBQ.
The Three Cheese was salty and stinky. The BBQ had a weird anise flavor. The Kickin' Ketchup was delicious, with just the right amount of tang. Honestly though, it tasted like barbecue sauce, not ketchup.
By the way, be careful with pouring the flavor powder; a pack contains too much of the stuff.
A bag of Shake Shake Fries costs Php 60.
Try it and judge for yourself.