It's my personal experience that a player willing to spend a feat to improve a save would prefer to improve their low save.

This feat does nothing for a Rogue's Reflex or a Cleric's Will.

A lot of characters already have the one save which they automatically pass, so, for them, this is basically +2 to two saves.

If you don't allow for this feat to meet pre-requisites, I don't think most characters will take it. At least not before level 12 or so, after you're gotten the core feats for your build. As someone else said, it'll be less popular than Imp Initiative.

If you do allow for the feat to meet pre-requisites, then I'd suggest buffing the existing ones from +2 to +5. This also makes the feats better reflect their names. I mean, I don't expect someone who is said to have lightning reflexes to have just slightly better reflexes.