Sisa's secret is that this bar is a cheat. I'm supposed to be sampling "pure" chocolate bars. That is, not chocolate with any other flavors added, like fruits, nuts, peppers, etc. On the other hand, only a few of the bars are really pure. They often have ingredients other than cacao and sugar. Some add salt, some add vanilla. Some add emulsifiers, or other things that I don't completely understand what chemically they do to the bar. They still work for me, because they are not adding those other things to make a flavor other than a chocolate bar flavor.
The Sisa's Secret is a 70% cacao bar with vanilla added. When I tasted it, I noticed that enough vanilla is added to give it a taste of actual vanillaness. In fact, if you look at the smaller print at the bottom of the wrapper you can see it is touted to be a dark chocolate bar "with vanilla." So I think this bar crosses the line between a chocolate bar that has some small amount of vanilla to adjust the chocolate taste to a bar that is trying to add actual vanilla flavor. Which violates my arbitrary rule.
That being said, it's good! Vanilla and chocolate are flavors that go well together. It gives this bar a very smooth, almost cool, taste. So if you don't give a shit about my arbitrary rules (and let's face it, who other than me does?) then it is a good one. It's only a cheat if you're someone like me with obsessive rules surrounding new year's resolutions.