It's not *totally* worthless as a +1 feat, but you're still probably better off trying to get 13 or 15 in one of your secondary scores to boost at the same time as your 17 if you're trying to be optimal. 3 damage per fireball target (which is the very highest utility of this, pretty much every other case where it matters, it matters less) isn't as significant as +1 to your Dex, Con, or Wisdom modifier.
You're best off going with stats like:
17 Cha
15 Dex
14 Con
10 Wis
9 (barf) Int
and getting to 18 Cha / 16 Dex at level 4 rather than taking a non-impactful +1 Cha feat.
In general I don't like Tiefling for Sorcerers. That +1 Int is a big waste, racial bonuses should only be applied to stats that are 13 or higher at point-buy. If you want a Sorcerer with a dark background & some good racial spells, go with a Half-Drow.