I bought 2 of these for my Bass Strait crossing. I can't report on how well they work as we didn't need them!
I hear lilo's are all the rage at the moment (from KMart)
Alex79, you really need to try one on or perhaps and make sure it's comfortable. The one you are looking for is simply a boat one with light that the manufacturers have bothered to get CAA approval for. Price wise not too bad, the going rate for boat jackets is around $70 plus this one has a water activated light.
I recommend if you are getting one to purchase it from Mendelssohn's; if they don't have it, they can usually get things shipped from OS in 5 days or less and they often discount below their advertised Internet price. We purchased a liferaft from them a few years back and were very happy, plus a transponder more recently.