Normally, vanilla is used in baking and desserts as a flavour enhance. Similar to salt, vanilla tends to bring out flavour qualities of other foods that otherwise wouldn't be noticeable. I was hoping that it would do the same thing for espresso.
My first impression was that it had a great aroma. The familar vanilla quality smelled great alongside the complex coffee notes. Unfortunately, it was lost in the tasting. Espresso is quite forward in taste, and generally has no trouble telling you what it wants you to know. The taste was present, but it didn't bring anything new or interesting to the shot.
Vanilla's superpower just isn't effective here. To put it in nerdy X-men terms, espresso is magneto's helmet that prevents against Professor Xavier's vanilla psionic attacks. Professor X, you'll have to stick to baking cookies with Jean Grey.