I actually always compare from buy gems in shop.
If we calculate like this:
100coins atlantis = 350 gems.
it means 350x3 = 1,050 gems
so, another plus 300gems, total = 1,350 gems.
and additional great sources = World Flask Energy 3x, per Flask it cost 100 gems, 100x3 = 300 gems.
All Total gems (summary) = 1,650 gems.
So, I think it worth.