The main question is, is it a limited gacha mechanics (at least the 2 free Centy) like the 55x gacha or will they do every rarity growth gacha like this with centy and all?
If it is, it's worth it. 2 Centies is 2 Centies. If it's not, it's not that worth it and it's better to wait for gacha with more interesting girls (at least, according to everyone own tastes).
60 FG for 2 Centies once is a good deal, 60 FG for 2 Centies every two weeks is a trap like the R-medals Centies.

I think it will be a once deal just to promote the new Rarity Growth gacha rates like they do with the 1st 55x gacha to promote the new event gacha rates.