The effect of the spell has been updated, but no one posted about it. Sony nerfed this spell at some point. I recently got it on my druid and was under the impression that it still did a 600 point direct heal that could crit for 1200. That is no longer the case.
The new effect is a Heal Over Time buff. It heals for 393 per tick. I still procs quite often, so it's basically a constant HoT in the Songs window.
I was rather disappointed when I tested it for the first time.