The best use of extract gift is if you are a demon or your cohort/familiar/friend/cousin is a demon. Get them to agree and use the +DC effects for benefit.
Have your Demon Pal auto fail on a fully buffed extract gift, now he's got a boat load of effects to monitor the "beneficiary" of the spell.
They still get a save for the demand right? There are better ways of telepathy.
A competence for the skills is nice, but the enhancement bonuses are worse than a belt of magnificence (albeit cheaper). This doesn't seem awesome to me.
There are better ways to get telepathy yourself, true, but lets take a look at what we're actually getting:
We get a constant Status spell, can have our demon see through the target's eyes and hear what it hears, can telepathically communicate with the target, and can cast demand on the target 1/day. Minimum resources expended per casting? 100 gold and 4 Exp. That is not at all a bad trade.
The enhancement bonus option isn't really where the gold is with this spell. Its the skill bonuses that are really neat. The enhancement bonuses only really become viable if you turn it into a supernatural effect via dweomerkeeper or somesuch, because then its free (no gold no xp = way better).
The fact that the enhancement bonuses are smaller (by 1) than a belt of magnificence on full tilt isn't so bad. 5 Enhancement + 5 Inherent = +10, and we only care about even ability scores, generally, that +11 you get from having the belt instead really doesn't help you all that much if you end up with a 21 in some stat.
That Quasit Familiar just became a massive Skill Booster...
Another reason why familiars are awesome!
-edit-
Another thing, the spell is caster level capped at +5 at level 20 for the enhancement bonus (or +10 skill at level 20 for skill bonus).
Caster level capped. We know how to get around that. Lvl 20 Red Wizard + Reserves of Strength = CL 48. Thats a maximum enhancement bonus of +9. Note that we only need CL boosting chicanery to get a benefit on the skill side, its max is 1/2 caster level, +24 enhancement to a skill isn't so bad.
Unfortunately we run into problems with that due to this text:
The donor demon's ability modifier for the corresponding score must be atleast twice that for the granted bonus. Thus, to grant a +2 bonus to dexterity you must extract essence from a demon with a Dexterity score of at least 18 (such as a marilith).
-snip-
The donor demon's ranks in the selected skill must be at least twice the granted bonus.
To get a +9 bonus we need a demon with a stat of 46 which is unlikely unless we start talking about the unique ones. Kostiche in a rage (which he most certainly would be if you were forcible extracting gift on him) for example has a Str of 46, so we can net ourselves the full +9 str bonus by extracting a gift from him.
By extracting skills from Demogorgon we can get a +20 enhancement bonus to Spellcraft.
