I have previously rated Starbuck's Via instant coffee a solid 'Meh'. It's a pretty good, if over-priced, on-the-go coffee.
By contrast Vanilla Via is a emphatic 'Blurk!', followed by mouthwash to combat the persistent after-taste. If you use this stuff to make mixed or flavor melanges its offensive taste might be largely disguised. But if you want to just add hot water and drink, no. Just no. Don't do it.
While plain Via has an inoffensive one-note mild flavor, Vanilla Via tastes first of chemicals (a bit like dish washing soap), strange delayed sweetness and slightly burnt coffee sweepings. The after-taste is filmy and acrid. I cannot believe anyone would pay good money for this crap.