Well...
In and of itself, it's on the high side of power for it's level, but not brokenly so.
If combined with something that voids Daze, it becomes a pre-quicken (as it eats up your Swift action in the next round) that can be applied to any spell with no spell level adjustment. This puts it at seriously overpowered - one extra spell in round one, on par with a Metamagic Rod of Quicken Spell capable of doing the highest level spell you can cast in rounds 2+, and for a lot less of an investment in permanent recources.
If combined with something that operates independantly of initiative - such as Contingency - it approaches an "I go first" button - and at 12th (where this first works), going first gives you very good odds in a battle. Another power increment, this one pretty sizeable.
When combined with Foresight (which makes you never flat-footed for the duration) it becomes an "I go first" button. And at 17th, where this first becomes possible, going first puts your odds of winning at around 80% or so.
When combined with Foresight and Time Stop.... umm... what opponent?
It's not that it's a broken spell in and of itself....