Persistence of Memory also negates the extra recharge time added by skills like Distracting Shot.
This skill does not prevent interruption. Instead, it makes the interrupted spell immediately available for recasting. Keep in mind, however, that the Energy spent on the interrupted spell — as well as the time casting it — are still wasted.
Unless you need another stance, consider using Mantra of Resolve instead of this for general-purpose interrupt protection: the cost penalty from the Mantra is usually less than the cost of having to cast the spell twice (or more).
The best use for this skill may be to protect low energy spells with long recharge.