ValhallaGH
Explorer
If I have to choose between this feat and almost any other, I'd take this feat. The fact that you can't stack it with itself keeps this feat under control but it's still better than 90% (or more) of feats.Improved Aptitude
Human Barbarian. Human feat - this one (strength). First level - this one (constitution).
Third level - either this one or Power Attack, and that's actually a difficult choice.
Ability scores are the king of the d20 system. Everything depends upon ability scores, and getting those as high as possible is one of the fastest ways to the most power (access to higher-level spells is the other big one). As long as you've got a 40 in your abilities, you can pretend to be five or six levels higher than you really are. Heck, with a 40 in all abilities, a Commoner 1 can pretend to be a 7th level PC (AC 25, HP ~17, spear +15 attack for 1d8+22 damage, +15 to all saves and skills). The worst class in the game, at the lowest level that has stats, and he's doing a credible impression of a mid-level hero simply because he has (really) high ability scores.
A feat is either too good or required for a class to work correctly if every member of the class takes it. Weapon Finesse is common for Rogues and helps that class function as intended. Natural Spell is common for Druids and helps that class rule the game. Natural Spell is too good, since it's taken by the majority of druids and provides a massive (and unneeded) increase in character power.
This feat has great appeal to every character of every class. It will almost certainly be taken once by everyone. The benefits it provides are comparable to going up a level (leveling is better, but this feat makes a valiant attempt to equal it). This virtually screams "overpowered" and tells me that any DM that allows this feat needs to keep a very close eye on how and when it is used.
Good luck.