So, I picked up this flavor as one of the five 5ml bottles included in their $5 sample pack (You can get it for free with coupon code vaping360 - you only pay shipping) . It tastes like those blue raspberry sour straws that we've all had as kids, and most of the sour appears to be on the inhale, and the sweet blue raspberry is on the exhale. I haven't had any other blue raspberry flavors so I don't really have anything to compare it to.
Giving it 3.5/5 because while the flavor is good, whatever they use to make it sour carries over after you change liquid and it can make some really...interesting combinations. It would be best to use this flavor with a dedicated coil/tank that you use for fruit/candy flavors so that the sour doesn't carry over. I can speak from experience that a dessert flavor doesn't taste very good with a sour undertone.