I think it's worth it for advanced players but not for new ones. You will get 2 centies if you roll it twice, allowing you to raise a 6* from lvl 80 to 90. But you ma not have a 6* to use them before a while. It's better to wait for a better gacha I guess.
Also, note that you can buy 60 Petite Centy (you need 100 Petite Centy to make 1 Centy) for 6 FG every event (every 2 weeks).